Assemble sandwiches. Spread marshmallow fluff evenly over two slices of bread. Spread peanut butter evenly over the remaining two slices. Press one fluff slice and one peanut butter slice together so the fillings meet. Repeat with the remaining slices.
Butter bread. Spread the softened butter evenly over the outside of each sandwich.
Grill. Heat a skillet over medium heat. Place the sandwiches in the pan and cook for about 2 minutes per side, or until golden brown and crisp.
Serve. Transfer to a plate and serve warm.
Notes
Nut butter swaps. Any peanut butter or nut butter can be used.
Bread choice. Any sliced sandwich bread works well for this recipe.
Fluff vs creme. Marshmallow fluff and marshmallow creme can be used interchangeably.