Place marshmallow cream in a bowl.
Add food coloring (amount varies pending on the type of food coloring you use) and mix well. Set aside.
Take one slice of rainbow bread and spread peanut butter evenly on one side. Take a second slice of bread and spread colorful marshmallow cream evenly on one side. Combine to make a sandwich.
Enjoy your sandwich but take note, colorful food like this will attract unicorns and trolls so be careful!