• Preheat oven to 350º F. Line a cupcake pan with paper liners and set aside.

Make the cupcake batter.

• In a large bowl, whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt.
  1 ⅛ cup all-purpose flour, 1 cup granulated sugar, ⅜ cup cocoa powder, 1 teaspoon baking powder, ¾ teaspoon baking soda, ½ teaspoon fine sea salt
• To the dry ingredients add milk, oil, sour cream, egg, and vanilla. Stir until well combined. The batter will be thick, similar to the texture of brownie batter.
  3 ounces whole milk, ¼ cup vegetable oil, 2 Tablespoons full-fat sour cream, 1 large egg, 1 teaspoon vanilla extract, ¼ teaspoon peppermint extract
• Add boiling water to the batter, carefully mixing with a whisk until well blended. The batter will now be very thin.
  4 ounces boiling water

Bake the cupcakes.

• Pour the batter into the cupcake liners, filling each ⅔ full.
• Bake the cupcakes for 18-20 minutes, or until the tops sprigs back when gently poked and a cake tester inserted into the center of a cupcake comes out clean or with just a few moist crumbs.
• Let the cupcakes cool completely before frosting.

Make the frosting.

• In the bowl of a stand mixer using the paddle attachment (or in a large bowl using a handheld electric mixer), beat butter on medium-high speed until smooth. 
  1 cup unsalted butter
• Add peppermint extract and salt and beat on medium-high speed until blended.
  ¾ teaspoon peppermint extract, 1 pinch fine sea salt
• Add sugar slowly - half a cup at a time - beating well on medium speed and scraping the bowl often. When all sugar is added the frosting will be slightly dry. 
  3 cups confectioners' sugar
• Add milk and beat on high speed until the frosting is light and fluffy.
  3 Tablespoons whole milk
• Add food coloring (if using) and mix on medium speed until thoroughly blended.
  1 drop green gel food coloring

Decorate the cupcakes.

• Using a piping bag fitted with a piping tip or an offset spatula, pipe or spread frosting onto the cupcakes.
• Sprinkle mini chocolate chips onto the frosted cupcakes.
  2 Tablespoons mini chocolate chips