Preheat the oven to 350 F. Line a muffin pan with cupcake liners.

In a large bowl, combine the sugar, flour, baking soda, baking powder, salt, and cocoa powder.

Add the egg, milk, oil, and vanilla extract and beat on medium speed until fully combined, about 2 minutes.

Stir in the boiling water. The batter will be thin and runny.

Pour the batter into the prepared muffin pan and bake for 15 minutes or until a toothpick inserted into the center of the cupcake comes out clean.

Cool cupcakes in the pan for 10 minutes before transferring to a wire rack to cool completely.

In a medium bowl, beat the butter until smooth.

Add the powdered sugar, milk, and vanilla extract, and beat until combined.

Beat on high speed until light and fluffy.

Separate the frosting into three bowls. Add a few drops of blue gel food color to one of the bowls, a few drops of orange gel food coloring to a second bowl, and a few drops of green gel food coloring to the last bowl. Stir each bowl of frosting until the color is completely distributed.

Transfer the blue frosting to a piping bag fitted with a large star piping tip, the orange frosting to a piping bag fitted with a large round tip, and the green frosting to a piping bag fitted with a medium piping tip.

Cut 24 ½ inch pieces of black fondant.

Roll the pieces into logs to make Goofy’s ears.

Set aside until ready to decorate.

Pipe a swirl of blue frosting onto the top of each cupcake.

Pipe a swirl of orange frosting on top of the blue frosting.

Pipe a small swirl of green frosting on top of the orange frosting to make Goofy’s hat.

Sprinkle the nonpareils on top of the cupcake.

Gently press two fondant ears into the frosting on each side of the cupcake.