Step 1: Preheat the Oven

1. Preheat your oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

Step 2: Prepare the Chocolate Cake

1. In a large bowl, whisk together the flour, cocoa powder, sugar, baking powder, baking soda, and salt.
2. In another bowl, mix the buttermilk, vegetable oil, eggs, and vanilla extract.
3. Add the wet ingredients to the dry ingredients and mix until just combined. Gradually stir in the boiling water until the batter is smooth (the batter will be thin).
4. Divide the batter evenly between the prepared cake pans. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean. Allow the cakes to cool in the pans for 10 minutes before transferring them to wire racks to cool completely.

Step 3: Make the Peppermint Frosting

1. In a large mixing bowl, beat the softened butter until creamy.
2. Gradually add the powdered sugar, mixing on low speed until combined, then increase to medium speed.
3. Add the heavy cream, peppermint extract, vanilla extract, and a pinch of salt. Beat until the frosting is light and fluffy, about 3-5 minutes.

Step 4: Assemble the Cake

1. Once the cakes are completely cool, place one layer on a serving plate. Spread a layer of peppermint frosting on top.
2. Place the second cake layer on top and frost the top and sides of the entire cake with the remaining peppermint frosting.

Step 5: Garnish

1. Sprinkle the crushed candy canes over the top of the cake and gently press some into the sides for decoration.
2. Optionally, place whole candy canes around the base or on top of the cake for a festive touch.

Step 6: Serve

1. Slice the cake and serve it to your guests. Enjoy this festive treat!