Step 1: Preheat and Prepare Preheat your oven to 350°F (175°C). Line a standard 12-cup muffin tin with paper liners to ensure the cupcakes don’t stick and are easy to remove.
Step 2: Mix Dry Ingredients In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt. Make sure there are no large lumps of cocoa remaining.
Step 3: Combine Wet Ingredients In a separate medium bowl, whisk the egg, milk, vegetable oil, vanilla extract, and peppermint extract until well combined.
Step 4: Create the Batter Slowly pour the wet ingredients into the dry ingredients. Stir by hand or use a hand mixer on low speed until the mixture is just combined. Do not overmix.
Step 5: Add Boiling Water Carefully stir in the boiling water. The batter will be very thin and watery, but this is normal. The hot water helps dissolve the cocoa and creates a tender crumb.
Step 6: Bake the Cupcakes Divide the batter evenly among the 12 cupcake liners. Bake for 18 to 22 minutes, or until a toothpick inserted into the center comes out clean. Let them cool completely on a wire rack.
Step 7: Prepare Peppermint Frosting Beat the softened butter until creamy. Gradually add powdered sugar, heavy cream, and peppermint extract. Beat on high speed for 3-5 minutes until the frosting is light and fluffy.
Step 8: Frost and Decorate Once the cupcakes are entirely cool, pipe or spread the frosting onto each one. Immediately sprinkle with crushed candy canes before the frosting sets.