• preheat the oven to 350°F or and add 24 cupcake liners to a muffin pan.
• Make a white cake from either scratch or a box. Make according to the directions on the recipe or box. Once the cake is ready to put into the cupcake pan, split it into 3 bowls. You will have about 1 ½ cups per bowl.
• Add the blue and green gel food coloring to each color of food coloring, stir to mix well. Leave one bowl white.
• Use a cookie scoop (1 tbs size) or large spoon to scoop tablespoon portions into the cupcake papers. Use one scoop of each color of cupcake batter for a cupcake. This keeps the colors from mixing and getting muddy looking. Alternately you can wash the scoop between colors.
• Bake the cupcakes according to the directions on the recipe or box. Once the cupcakes are baked let them cool completely before frosting. 3-4 hours.

Frosting

• Mix together the softened butter. Beat with a hand mixer on low until creamy.
• Add one cup of powdered sugar, vanilla, and salt. Mix in. Then add the rest of the powdered sugar a cup at a time, mixing on low after each addition. Scrape the bowl half-way through. The frosting will be very heavy and thick at this point.
• Add 1 tbsp heavy cream and beat on medium to mix in. If the frosting is still too thick to pipe, add 1 more tbsp heavy cream. Be careful to not add too much cream
• Split the frosting into 2 bowls and add enough gel green and blue food coloring to achieve the color you want in each bowl. Mix well until frosting is evenly colored. Scrape the bottom of the bowl to make sure there are no dark streaks on the bottom. I use a hand mixer.
• Make the monster's horns out of dark chocolate using the silicone mold while the cupcakes are cooling.

Decorating the Cupcakes

• Put the large piping tip on a large 18-inch pastry bag.
• Put about 1 cup of each color of frosting into a 12-inch pastry bag, Don't overfill the bag. Cut about 1 inch of the tip-off of the bag and gently flatten the bag to be about 1/2 inch thick. Half of the frosting is enough for 8- 10 cupcakes. Consider doubling the recipe for swirled icing. I use a tall coffee travel mug to hold the pastry bag open while I'm filling it.
• Stack the 2 flattened bags together and insert them into the large pastry bag with the piping tip.
• Squeeze the bag until you see both of the colors coming out. Pipe the frosting in a swirl pattern onto each cupcake. Add sprinkles, the horn, and eyes.