This pastel-colored unicorn cake is 3 layers of tasty fun and magic. Made with an upgraded boxed cake mix recipe and a whipped cream cheese frosting, this cake is as tasty as it is pretty.
I eagerly took on the task of creating a birthday cake for my unicorn-loving niece, inspired by my desire to craft an easy unicorn cake. To start, I enhanced a cake mix to ensure it was not only delicious but also yielded enough batter to fill three 8-inch cake pans. This would give us the ideal unicorn cake height and plenty to share with all the partygoers.
For the delightful filling of this colorful unicorn cake, I used a box of cook-and-serve vanilla pudding, prepared and chilled as per the box instructions. This handy shortcut is a personal favorite and a go-to for my birthday cake crepes recipe as well. It offers a taste similar to homemade pastry cream without the added effort.
When all these components come together – the cake, the filling, and the frosting – they harmonize to create a heavenly rainbow unicorn birthday cake that's not only visually stunning but also incredibly light, fluffy, moist, and, most importantly, utterly delicious.
🍯 Why This Recipe Works
- It's easy. While there are several time consuming steps, the actual work needed to make this cake is fairly simple. Perfect for an at home baker.
- It's a cheaper alternative. You can buy a cake from a store or professional, or you can make one at home. Making your own cake means keeping a little more money in your wallet and adding more memories and love in every slice.
- You can customize it. Change up the colors or flavors as you want and really make this recipe your own!
Yellow Cake Mix- This will be the base of the cake recipe, making it easier and more simplified. You can use Yellow or white cake mix.
All-Purpose Flour- For added gluten, it gives us a better structure.
Instant Pudding Mix- You will need the dry mix from the pudding box. Do not prepare it beforehand.
Pudding- You will need Vanilla Flavored Cook and Serve Pudding (plus the milk to make it).
Cream Cheese- Adding cream cheese will give us a great flavor, but it also helps the frosting to remain stable enough to pipe decorations with.
For specific ingredients and measurements, please see the recipe card below.
Step 1: Preheat your oven to 350 degrees F.
Step 2: Cut some parchment paper circles the size of the bottom of your cake pans and then spray the sides and bottom of the cake pans with non-stick cooking spray before placing the parchment paper in and spraying them again. This will keep the parchment paper in place so that it doesn't curl up.
Step 3: Set the pans aside and prepare the batter.
Step 4: In a very large mixing bowl, combine the dry cake mix, flour, sugar, salt, and boxed pudding mix with a whisk.
Step 5: In another mixing bowl, blend together the eggs, oil, milk, and vanilla.
Step 6:Add in the sour cream.
Mix until combined.
Step 7: Add the wet ingredients to the dry ones.
Whisk together until well blended and no flour streaks remain.
Baking and Leveling
Step 8: Divide the batter between small bowls and add food coloring to each.
Stir until the desired colors have been achieved.
Step 9: Spoon the batter into the cake pans, a little at a time from each color until all pans are filled evenly and no unused batter remains.
Use a toothpick to swirl the colors around if desired.
Step 10: Bake in the oven at 350 degrees F for 25-30 minutes or until a toothpick can be inserted and come out clean.
Step 11: While the cakes are in the oven prepare the vanilla cook and serve pudding according to package instructions and place plastic wrap over the surface of the cooked pudding as it cools to prevent thick skin from forming.
Step 12: Once the cakes have finished baking allow for them to cool in the pans for 10 minutes before flipping over onto a cooling rack.
Step 13: Allow to cool completely before using a bread knife to level the tops.
Step 14: Prepare the frosting as directed by the recipe card below. Place 2 cups of frosting in a covered bowl in the fridge for later (this will be the unicorn hair).
Step 15: Place some frosting into a piping bag or Ziploc bag with the end snipped off and on two layers of cake make a full ring around the leveled top.
Step 16: Spoon your pudding filling into these circles. The frosting will help to keep the pudding from leaking out when stacked. Try not to overfill the cake layers.
Stacking and Decorating
Step 1: Stack the three cake layers so that the filling is between two layers and the empty layer is the one on top.
If you feel your cake needs more stability you can trim a few (like 3) paper straws to just a little shorter than the height of the cake and place them around the center of the cake, going through the layers like dowels.
You can also freeze the cake at this point if you're making it in advance or wanting it to be more solid when you apply the frosting layers (less crumby that way).
Step 2: When the cakes are stacked and sturdy, Pipe some white frosting around the centers and sides of the cake. Make sure to get the top as well.
Step 4: Take a long flat surface like a cake lever and go around the sides of the round cake, holding the leveler at a slight angle towards the cake, about 45 degrees.
This will push the frosting into the cake as it smooths it out so it can help to fill in gaps and holes. Go around until the cake is covered in a thin layer. It's perfectly fine for crumbs to be stuck in the frosting.
Step 5: Chill the cake and the frosting at this point before doing a final frosting layer. If your cake is frozen solid, you may be able to get away with adding a thicker frosting layer now that the crumb layer is chilled against the cold cake.
Step 6: Add a thick layer of frosting around the sides and top and level it out until smooth. I say thick but really you want it no more than ¼ inch thick as your only goal is to make the frosting thick enough that the cake isn't poking through the sides. The top doesn't matter and can be left as a crumb layer because you will be covering it in unicorn hair frosting.
Step 7: Place the cake back into the fridge as you prepare the hair colors.
Step 1: Remove the chilled frosting you set aside earlier and mix it with any unused white frosting you have leftover from frosting the cake.
Step 2: Divide the frosting by however many colors you want and add some food coloring to each, mixing until blended.
Step 3: Place each frosting into its own piping bag with a fitted tip. A different tip should be used per color as it helps to make things less confusing and more unique.
Step 4: Arrange the bags of frosting in order of largest tip to smallest tip as this will make it easier to grab and use.
Step 5: Grab the cake from the fridge and set it in front of you. Plan out how you want the hair arranged. Do you want the full top covered or just a strip down the middle? Do you want large bangs or small ones? Etc.
Step 6: Once you've got an idea, go for it! Grab the largest tip and make several circles starting in the front and working your way back. Set down the frosting bag and grab the next tip.
Step 7: Use it to fill in some of the gap areas by making circles that are smaller or make stars by pressing down on the tip and lifting straight up. Continue this process until you get to your last color and use that to fill in any of the small gaps still left.
Step 8: Add sprinkles to the hair if desired.
Step 9: Add the unicorn horn and ears; if you haven't already, add the unicorn eyelashes too. These usually come with unicorn kits but can also be made with melted chocolate too.
Slice, Serve, and Enjoy!
~Happy Birthday To You~
🍴 Recipe Tips
When making this cake you must have a very large mixing bowl. A standard-sized large mixing bowl is a very tight fit for all of these ingredients and a bowl bigger than that is ideal. In our family, this is usually the bowl reserved for Momma's Potato Salad.
You don't have to divide and color the batter if you don't want to, but I think it makes for a fun and unexpected surprise to tie in the pastel colors for this DIY rainbow unicorn cake. Even just dying each layer its own color is a cool idea. Using gel food coloring for the batter and frosting is ideal for getting vibrant colors without adding in too much moisture. Not only that but a little gel coloring goes a long way.
Make sure that the pudding filling is either cooked and cooling before you begin making the cake layers or shortly thereafter so that the cake is cooled around the same time. This is especially important if you plan to bake and stack on the same day but both the layers and the filling can be prepped a day in advance. Freeze the cake layers while the filling remains in an airtight container in the fridge.
Using a large bread knife to level the cakes is great but my favorite trick is to cut off the dome of the cake before removing the layer from the cake pan. This way, you can use the cake pan as a level gauge so that the cake tops are all cut off to an even height. You can choose to remove the layers and use a Wilton cake leveler tool for thinner but flatter layers if desired.
Smoothing out the frosting for the unicorn is a big part of getting the unicorn to look right. While using an actual frosting smoother is ideal, I have used (clean) wooden rulers in the past so don't overlook basic house items and office supplies when in a pinch.
most bakers will agree that a unicorn cake looks best when there is a minimum of 3 layers. This gives you plenty of space for hair and facial designs.
You will need Wilton 1M, 21, & 199. You can use any tips you want to, but these three will give you the best variations in size and shape.
You can use anything from cardboard to fondant. With unicorns becoming so popular, you can even buy kits from Amazon and from Walmart where plastic unicorn horns are included.
❤️ More Delicious Cake Recipes
If you tried this Rainbow Unicorn Cake, please leave a ⭐️ star rating and share your feedback in the 📝 comments section below. I would truly appreciate it!
Rainbow Unicorn Cake
- (3) 8 inch cake pans
- 1 box (15.25oz) Yellow Cake Mix (just the dry stuff!) ($1.00)
- 1 cup All-Purpose Flour ($0.08)
- 1 cup Granulated Sugar ($0.22)
- ¾ teaspoon Salt ($0.08)
- 1 box (3.4oz) Vanilla Flavored Instant Pudding Mix ($0.98)
- 4 large Eggs ($0.32)
- 1 cup Sour Cream ($0.80)
- ½ cup Vegetable Oil ($0.24)
- 1 cup Milk ($0.19)
- 1 Tablespoon Vanilla Extract ($0.04)
- 1 box Vanilla Cook and Serve Pudding (Prepared) ($1.36)
- 2 ¾ cups Heavy Whipping Cream ($2.72)
- 1 cup Powdered Sugar ($0.23)
- 8 ounces Cream Cheese, softened ($1.98)
- 1 teaspoon Vanilla Extract ($0.02)
- Food Coloring in Desired Colors
- Preheat your oven to 350 degrees F.
- Cut some parchment paper into circles that can fit at the bottom of your 8 inch cake pans. Spray cake pans with non-stick cooking spray and lay the parchment circles inside. Spray again with cooking spray and set aside.
- In a large mixing bowl whisk together the cake mix, flour, sugar, salt, and boxed pudding mix.
- In another mixing bowl blend together the eggs, sour cream, oil, water, and vanilla.
- Add your wet ingredients to the dry ones and mix until well combined and no flour streaks remain.
- Divide the batter between small bowls and add food coloring to each one. Mix until the color is evenly distributed.
- Divide the batter evenly between your three cake pans by using the same scoop measure (I use a small cookie scoop) and adding a mixture of each color into each pan. Each cake pan should look blotchy like it's a tie-dye of fun rainbow colors. Use a toothpick to lightly swirl the colors together if desired.
- Bake in the oven at 350 degrees F for 25-30 minutes or until a toothpick can be inserted into the center and come out clean.
- While the cakes are in the oven, prepare the vanilla cook and serve pudding according to package instructions and cover the hot pudding with plastic wrap to prevent a skin from forming. Remove it from heat and allow it to cool until ready to use or place it in the fridge.
- Once the cakes have finished baking allow them to cool in the cake pans for about 10 minutes before flipping over onto a cooling rack to finish cooling completely.
- Allow them to cool on the racks upside down and make sure to remove any parchment paper from the bottom of the cake.
- Once the cakes are completely cooled, flip them over onto a cutting board and level the tops with a large bread knife.
Prepare the frosting
- In a large mixing bowl cream together the cream cheese and powdered sugar until just combined. Do not overmix.
- In another large mixing bowl beat the heavy cream and vanilla until stiff peaks form.
- Add the cream cheese mixture to the whipped cream and beat again until combined. Do not overmix.
- Remove 2 cups of frosting and set aside (covered) in the fridge. This will be divided and colored later for the unicorn mane.
- Place two topless cake layers in front of you and leave the other off to the side.
- Place some frosting into a pastry bag or Ziploc baggie with a corner snipped off.
- Make a circle around the rim of the tops of them both.
- Spoon in your cold and chilled vanilla pudding. Spread it around so that it fills the circle and is pretty even looking.
- Stack the three cakes on top of each other by placing one pudding topped cake on top of the other and the one you had set aside on top of the other two. Try to get them to stand as straight as you can. If needed, place everything into the fridge to chill for one hour so it holds up better. You can also freeze the cake at this point and chill the frosting until ready to use.
- When the cakes are stacked and sturdy, pipe the white frosting around the outside where the middles are and go around the cake with a flat leveler or surface (a wooden ruler works okay in a pinch). Angle it slightly so you're pressing into the cake while removing excess frosting. This should fill in any gaps so the cake is level on the sides.
- Frost the entire cake with a nice thick layer of white frosting so that it is about ¼ inch thick and you can't see the cake poking through. Go over it again with your flat leveler as much as needed to get it to look as desired. Don't forget to level out the top.
- Place the cake in the fridge to chill as you prepare the colored frostings.
- Remove your chilled frosting and add it to any leftover white frosting you may have (assuming it's not filled with cake crumbs).
- Divide the frosting by however many colors you want in the hair and then add food coloring to each bowl and mix until well blended.
- Place each frosting in it's own pastry bag with fitted tip. A different tip per color really helps to make things less confusing. You want to use the tips advertised as borders or stars as these look nicer than the round ones or leaves (unless you want to add leaves on purpose).
- Arrange each bag once filled and fitted to the side in the order of biggest tip to smallest. This makes it easier to grab and use.
- Bring your white frosted cake out of the fridge and set it in front of you. Plan how you want the hair to go. Do you want to cover the whole top or just a strip cascading down the side at an angle? Most unicorn cakes have bangs.
- Once you have an idea in mind, grab your largest tip and pipe large circles in the direction you want them to go. Try to keep them spaced out so other shapes can fill the gaps.
- Grab the next color and add smaller swirls or stars around the large ones in the gaps you provided, leaving space for the next colors too.
- Repeat until there is only one small frosting tip left and use it to carefully fill in any white spots in the hair.
- Add any sprinkles (if using) and place in the ears and horn. If you haven't already, add the eyes. These often come in kits with the horn and ears but if not, you can mix a little frosting with black food coloring or use melted chocolate.
- Slice, serve, and enjoy!