Preheat your oven to 350°F (175°C) and line your cupcake tin with colorful cupcake liners.

In a mixing bowl, whisk together the all-purpose flour, granulated sugar, light brown sugar, unsweetened cocoa powder, Dutch-process cocoa powder, baking powder, baking soda, and salt until evenly combined.

In another bowl, crack the eggs and mix with buttermilk, vegetable oil, and vanilla extract until smooth.

Heat one cup of water, dissolve the espresso powder, and stir the mixture into the wet ingredients.

Gradually add the dry ingredients to the wet mixture, stirring gently until just combined.

Fill each cupcake liner about two-thirds full with the batter and bake for 18-20 minutes, until a toothpick inserted comes out clean.

Allow the cupcakes to cool in the tin for 5-10 minutes before transferring them to a wire rack to cool completely.

Microwave the heavy cream until steaming, then pour it over the chopped Andes mints and whisk until smooth.

Core the center of each cooled cupcake and fill with ganache, then replace the core piece.

In a mixing bowl, beat the unsalted butter until creamy, then gradually add powdered sugar and mix well.

Incorporate peppermint extract, heavy cream, food coloring, and crushed chocolate wafers until the frosting is light and fluffy.

Pipe the mint chocolate buttercream onto each cupcake, adding an Andes mint on top for garnish.