Preheat the oven to 350 degrees F and line a cupcake pan with 4 paper liners.
In a medium bowl, whisk together the flour and baking powder.
In a separate bowl, beat the softened butter and sugar until light. Add the egg and vanilla extract, then mix until smooth.
Pour in the milk and stir to combine. Add the dry ingredients and mix just until no streaks remain.
Divide the batter into three small bowls. Leave one bowl plain, tint the second bowl yellow, and tint the third bowl orange.
Drop spoonfuls of each color into the liners, then use a toothpick to gently swirl the colors together.
Bake for 15 to 18 minutes, until a toothpick inserted in the center comes out clean. Cool completely.
Spread vanilla frosting on each cupcake and press three candy corn pieces on top.