Coconut-Lime Rainbow Whoopie Pies

Ingredients

• 1/2 cup butter, softened
• 1 cup sugar
• 1/2 teaspoon baking soda
• 1/4 teaspoon salt
• 1 egg
• 1 teaspoon coconut extract
• 1-1/2 teaspoons lime zest (about 1 lime)
• 2 cups all-purpose flour
• 1/2 cup buttermilk
• 1 cup powdered sugar
• 1/2 cup ground Fruity Pebbles cereal
• 1/2 cup marshmallow fluff
• 1 teaspoon vanilla