A triple layer cake with luscious buttercream frosting and chocolate ganache, this Peppermint Fudge Cake is the ultimate Christmas dessert. It's rich, decadent, and guaranteed to steal the show!
Heat the oven to 350°F. Spray 3 8-inch round pans with nonstick spray. Line the bottoms with parchment paper cut into a circle to fit the pan. Spray the parchment paper with nonstick spray and dust the pan lightly with cocoa powder. Tap out any excess and set aside.
In a medium bowl, combine the flour, cocoa powder, baking soda, baking powder, and salt. Stir with a whisk and set aside.
Add the chocolate to a small heatproof bowl and set it over a pot of barely simmering water. Stir continuously until melted and smooth. Remove from heat. Set aside to cool.
Using a stand mixer fitted with a paddle attachment or a handheld electric mixer beat the butter and sugar together on medium-low speed until light and fluffy.
Beat in the eggs, one at a time, mixing well after each addition. Scrape down the sides of the bowl as needed. Beat in the vanilla. Add the melted chocolate and mix until well incorporated.
With the mixer set to low speed. gradually add half the flour mixture, followed by the buttermilk and coffee, and then the remaining flour mixture. Beat just until combined. The batter will be thick.
Divide the batter evenly between the 3 prepared pans. Use an offset spatula to spread the batter all the way to the edges of the pan and smooth out the surface. Bake for 30 to 40 minutes, or until a toothpick inserted into the center comes out with only a few dry crumbs. Take extra care not to overbake or the cake layers may crumble.
Cool the cake in the pans for 10 minutes, then invert the cakes onto a wire rack to cool completely.
Make the frosting
In the bowl of a stand mixer fitted with the paddle attachment or a large mixing bowl with a handheld electric mixer, beat the butter on medium-high speed until creamy and pale in color, about 5 minutes.
Add half the confectioners' sugar and beat on low speed just until the sugar has fully moistened, then turn the speed up to medium-high and beat until well incorporated, about 3-5 minutes.
Add the remaining confectioners' sugar and beat on low speed just until the sugar has fully moistened, then turn the speed up to medium-high and beat until well incorporated, about 3-5 minutes.
Add the peppermint extract. Turn the mixer on low speed and slowly add 3 tablespoons of the heavy cream. Turn the mixer up to medium-high and beat until the cream is well incorporated, about 3-5 minutes. (After 2 minutes stop and scrape down the sides and bottom of the bowl then continue mixing.)
Check the consistency of the frosting and add more cream, ½ tablespoon at a time, if needed. The frosting should be soft and spreadable but not so loose that it doesn't hold its shape.
Place 1 cup of frosting in a small bowl and cover with plastic wrap, set aside.
Assemble to cake
Place one cake layer onto a serving platter. Add a generous amount of frosting and spread it to the edge with a spatula. Repeat with a second cake layer, topping it with a generous amount of frosting. Add the third cake layer and cover the top and sides of the cake with frosting. Press crushed candy canes into the sides of the cake near the bottom and coming up less than halfway. Set the cake in the freezer for 20 minutes.
Make the ganache
Place the chocolate, butter, and corn syrup in a medium heatproof bowl set over a pot of barely simmering water. Stir until melted and smooth. Remove from heat and let cool for 5 minutes.
Pour ganache on the top center of the chilled cake. Use an offset spatula to carefully spread the ganache to the edge, gently nudging it over the lip so that it drips over the sides of the cake. Set the cake back into the freezer for 10 minutes.
Make the swirled frosting
Divide the remaining frosting in half and color one half with red food coloring. Transfer each frosting to its own piping bag. Insert a star piping tip into a larger piping bag. Cut the ends off each piping bag holding the frosting and insert them side by side in a large bag containing the tip. Pipe swirls on top of the cake. Keep the cake refrigerated and remove 30 minutes prior to serving.
Notes
Dutch-processed cocoa: It is extremely important that you use Dutch-processed cocoa. Regular cocoa will not work with this recipe.
Unsweetened chocolate: I don't recommend using anything other than unsweetened chocolate. Bittersweet or semisweet will be too sweet for this recipe.
Coffee: Coffee enhances the chocolate flavor. It doesn't make the cake taste like coffee. However, if you'd rather not use it, you may use an additional half cup of buttermilk in its place.
Frosting: I used my favorite vanilla buttercream and replaced the vanilla with peppermint extract. I have a ton of tips in that post to help with achieving a luscious texture.
Corn syrup: Corn syrup adds a lovely shine to the ganache and is completely optional.
Cake layers: Because of the texture of this cake, cold cake layers are the easiest to work with. Once the layers have cooled, wrap them tightly in a few layers of plastic wrap and pop them into the freezer for a few hours or up to 2 days. When you are ready to assemble the cake, set the wrapped layers on the countertop for 30 minutes to thaw slightly. Continue with frosting and layering the cake.
Different pans: I've had readers try to bake this cake in bundt pans and mini bundt pans. Not all cake recipes will work with bundt pans and this is one that won't. The layers are too fragile. I only recommend making this cake exactly as written in the recipe.
Bake-even strips: For perfectly baked cake layers, I always suggest using bake-even strips. They are cloth strips that you soak in water and wrap around the cake pans. They promote even heating around the pans allowing the layers to bake up moist and level.
Make ahead tip
Wrap baked and cooled cake layers tightly in plastic wrap and store them in the refrigerator. Assemble and frost the cake within 2 days.
The frosting can be prepared, covered, and refrigerated overnight. Bring to room temperature and re-whip in needed.
The frosted cake can be frozen for up to 2 months. Thaw it overnight in the refrigerator and let it come to room temperature just before serving.