Step 1

Preheat the oven to 350°F (175°C) with a rack in the center position. Grease and flour three 8-inch (20-cm) cake pans and set aside (*see the note section for tips if you do not own three pans).

Step 2

In a medium bowl, sift together the flour, cocoa powder, baking powder, baking soda, and salt and set aside.

Step 3

In a bowl of a stand mixer fitted with a paddle attachment, beat together the oil and sugar on medium speed for 2 minutes. Over medium speed, add the eggs, egg yolk, vanilla, and peppermint extract. Stop the mixer and scrape down the bowl.

Step 4

Turn the mixer to low and add the flour mixture in three batches, alternating with the milk, beginning and ending with the flour mixture. Stop the mixer and scrape down the bowl. With the mixer on low, slowly pour in the hot coffee. Mix on medium-low for no more than 30 seconds, or until combined. Scrape down the bowl to ensure it is incorporated evenly.

Step 5

Evenly divide the batter (*see the note section on how to do this!) among the prepared cake pans. Bake for 23 to 25 minutes, or until a toothpick inserted into the center of the cake comes out clean. Let them cool on a wire rack for 10 to 15 minutes before removing the cakes from their pans. Allow the cake layers to cool completely before decorating. *If you are preparing this cake in advance, double-wrap the cooled cake layers in plastic wrap before refrigerating or freezing.

Step 6

Place the candy canes in a large resealable freezer bag and squeeze out any excess air. Using a rolling pin, crush the candy canes into very small pieces (*you don’t want any of the pieces to be too large or they will be chewy, rather than crunchy). Set aside.

Step 7

Place the egg whites and sugar in the bowl of a stand mixer. Whisk them by hand to combine. Fill a medium saucepan with a few inches of water and place it over medium heat until lightly simmering. Place the bowl on top of the saucepan to create a double-broiler, making sure the bottom of the bowl doesn’t touch the water. Whisking intermittently, heat the egg mixture until it reaches 160°F (70°C) on a candy thermometer or is hot to the touch.

Step 8

Using the stand mixer, beat the hot egg white mixture over high speed for 8 to 10 minutes or until it reaches stiff peaks. Over low speed, slowly add the chunks of butter (a tablespoon or two at a time). Once incorporated, turn the mixer to medium high and beat until the buttercream is silky smooth, 3 to 5 minutes. Add the vanilla and peppermint extract and beat for an additional 30 seconds. Using a spatula, fold in the crushed candy canes.

Step 9

Level the cooled cake layers with a long serrated knife and choose which layer will be the bottom (tip: pick the sturdiest layer). Place it on a cake plate, turning table, or serving dish. Spread on roughly ¾ cup (180 ml) of the buttercream with an offset spatula. Top with the next layer of cake and repeat, ending with the third layer (tip: pick the most level, attractive layer for the top).

Step 10

Frost the sides and top of the cake with the remaining buttercream (*if time permits, frost a thin crumb coat, refrigerate for 15 to 20 minutes, and finish with the remaining buttercream). A straight-sided frosting spatula and bench scraper are great for producing smooth sides. Refrigerate the cake, uncovered, for 20 to 25 minute before glazing.

Step 11

In a small saucepan, combine the chopped bittersweet chocolate, cream, and corn syrup. Place over medium-low heat and stir continuously until the chocolate has melted. Remove from the heat and whisk gently until smooth and shiny. Stir in the peppermint and vanilla extract. Allow the glaze to cool until it is thick, yet can still drizzle from a spoon - about 10 minutes. (*If the glaze is too hot, it will drip too quickly and potentially melt the frosting. If the glaze is too cool, it will set too thickly and won’t drip over the sides).

Step 12

Gently spoon the chocolate glaze over the edges of the cake, letting it drip over the edges. Spoon the remainder of the glaze in the center of the top of the cake, spreading and smoothing it into a thin even layer with a small offset spatula. Allow the glaze to set at room temperature before topping with garnishes.

Step 13

Using your hands, decorate the cake by gently pressing crushed candy canes into the buttercream on the bottom of the cake. Top the cake with peppermint sandwich cookie halves and additional candy cane pieces. *Important Storage Note: The exposed candy cane pieces and cookies will gain moisture and become chewier (and less crunchy), so it is best to do this just before serving if possible.

Step 14

Serve the cake slightly chilled or at room temperature. For clean slicing, run a long thin knife under very hot water for several seconds, dry the knife well, and proceed to slice the cake into wedges. Repeat for each slice.