In a large mixing bowl, beat the softened butter until smooth and creamy.
Add the powdered sugar, marshmallow fluff, vanilla, and Princess Emulsion. Mix on low until combined, then increase to medium speed and beat until fluffy.
If the frosting is too thick, add heavy cream one tablespoon at a time until you reach your desired consistency.
Mix in a few drops of pink food coloring until evenly tinted and no streaks remain.
Spoon into a piping bag and swirl onto cooled cupcakes, cakes, or cookies.
Notes
This makes enough for about 18–24 cupcakes or one 9×13 cake.