Chocolate Yule Log

Whip 1 ⅔ cups confectioners' sugar, ½ cup butter, coffee-flavored liqueur, 1 ½ tablespoons cocoa powder, and 1 pinch salt together in the bowl of a stand mixer fitted with the whisk attachment on high speed.

Transfer filling to a separate bowl; stir in mascarpone cheese until combined. Set aside. Clean and dry the stand mixer bowl.

Preheat the oven to 400 degrees F (200 degrees C).

Brush a 13x18-inch rimmed baking sheet with a little melted butter. Line the baking sheet with parchment paper; brush parchment with remaining melted butter.

Whisk ½ cup cocoa powder, flour, and ½ teaspoon kosher salt together in a bowl, making sure to break up any clumps.

Place eggs in the clean stand mixer bowl fitted with the whisk attachment. Add sugar; whip until fluffy, thick, and very light in color, 2 to 3 minutes.

Add vanilla extract and ½ cocoa powder mixture; mix on low speed for a few seconds.

Add remaining ½ cocoa mixture; mix on low for a few seconds. Switch to high speed; mix until the mixture is moistened but not fully blended.

Pull off the whisk attachment and use it to whisk the batter by hand until evenly blended.

Pour batter onto the prepared baking sheet; spread out with a spatula, almost to the edges, but not quite. Tap the baking sheet on the counter several times to remove any large air bubbles.

Bake in the preheated oven until the top is dry and the edges start to pull away from the sides, 8 to 10 minutes.

Meanwhile, sift some confectioners' sugar onto a clean kitchen towel to cover an area slightly larger than the sponge cake.

Remove cake from the oven. Run a knife around edges of the baking sheet. Dust some confectioners' sugar over top of cake. Run a spatula under the parchment paper to make sure it's not stuck to the baking sheet.

Quickly flip the baking sheet on top of the sugared area on the towel to invert the cake.

Carefully remove the parchment paper, then sift more confectioners' sugar over cake.

Gently roll cake up inside the towel; set aside to cool for 15 minutes.

Carefully unroll the cooled cake. Dollop as much buttercream filling as you like on top, reserving some for later; spread to the edges.

Roll cake up over the filling, using the towel to lift it if needed.

Sprinkle more confectioners' sugar over top of log; wrap in plastic wrap. Refrigerate until firm, about 2 hours.

Pour hot cream over chocolate chips in a bowl; set aside for 1 minute, then whisk until chocolate is melted.

Cut log at an angle 3 inches from one end of log. Place log on a parchment-lined baking sheet.

Spread some filling on the angled slice; attach it to one side of the log.

Spread a layer of ganache all over cake, except for the swirls on the ends. Refrigerate until ganache firms up, 15 minutes.

Carve lines into ganache to create the appearance of tree bark using the tip of a knife. Refrigerate until completely chilled.

Dust with cocoa powder and confectioners' sugar before serving.