Preheat your oven to 350°F (175°C). Grease and flour the two 9-inch round cake pans.
In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.
In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy, about 3-5 minutes.
Add the eggs, one at a time, mixing well after each addition. Stir in the vanilla and peppermint extracts.
Gradually add the dry ingredients to the wet ingredients, alternating with the whole milk. Mix until just combined.
Divide the batter evenly between the prepared cake pans and smooth the tops.
Bake in the preheated oven for 25-30 minutes or until a toothpick inserted into the center comes out clean.
Remove from the oven and allow the cakes to cool in the pans for 10 minutes before transferring them to a cooling rack to cool completely.
While the cakes are cooling, prepare the frosting. In a medium bowl, beat together the powdered sugar and cocoa powder.
In a separate bowl, whip the heavy cream until soft peaks form. Gently fold the whipped cream into the chocolate mixture until smooth.
Once the cakes are completely cool, place one layer on a serving platter. Spread a generous amount of frosting on top, then place the second layer on top.
Frost the top and sides of the cake with the remaining frosting. Optionally, pipe decorated borders around the cake using the piping bag.
Finish by sprinkling crushed peppermint candies on the top and sides of the cake.