01 -
Place oven racks in upper and lower thirds and preheat to 175°C. Line 18 cupcake cups in two standard 12-cup muffin tins with paper liners.
02 -
Prepare cake batter according to package instructions. Divide batter in half and add red gel food coloring to one half, stirring until the desired shade is achieved. Alternate spooning white and red batter into liners until they are about half full (approximately 45 to 60 ml each).
03 -
Bake cupcakes for 18 to 20 minutes, rotating tins halfway through. Insert a toothpick into the center to check doneness; it should come out clean. Allow cupcakes to cool completely.
04 -
Beat softened butter and kosher salt with an electric mixer on medium speed until creamy, about 2 minutes. Gradually add confectioners' sugar in two batches, beating thoroughly after each. Incorporate heavy cream, vanilla extract, and peppermint extract, then beat on medium-high speed for 2 minutes until light and fluffy.
05 -
Using a small brush or long skewer, paint two lines of red gel food coloring inside a piping bag fitted with a 1.27 cm round tip.
06 -
Fill the prepared piping bag with frosting and pipe over cooled cupcakes. Garnish each with a mini candy cane or sprinkle coarse peppermint sugar atop.