In large bowl or stand mixer, combine powdered sugar, butter, cocoa and coffee liqueur. Mix well and transfer to separate bowl and add mascarpone cheese. Mix well to combine and set aside.

Preheat oven to 400 degrees F. Line 13x18-in. sheet pan with parchment paper and coat with cooking spray.

In bowl, combine cocoa powder, salt and flour. Whisk to break up clumps.

In separate bowl or stand mixer, whip eggs and sugar until fluffy thick. Mix in cocoa powder. Pour batter onto sheet pan and spread evenly with spatula, leaving room around the edges. Bake for 8-10 minutes until top is dry.

Remove cake from oven and run a knife around the edges to make sure it doesn’t stick. Dust clean kitchen towel with powdered sugar in shape of sheet cake. Quickly flip cake onto towel.

Remove parchment paper and roll cake up inside of the towel. Allow to cool for 15-20 minutes.

Unroll cake and dollop buttercream on top, reserve a little for later. Spread frosting over the edges and entire cake. Sprinkle powdered sugar on top and roll into log shape. Wrap log in plastic wrap and refrigerate until firm, about 2-3 hours.

In small pot, bring cream to boil. In bowl, combine chocolate chips and boiling cream. Let sit for a minute then mix until smooth and silky.

Unwrap plastic wrap from cake. Make an angled 3-in. cut down the cake. Apply butter cream on one side and stick the cut piece on the side to emulate a log. Spread ganache all over cake except the swirly ends.

Refrigerate cake for 20 minutes. Remove and use butter knife to carve lines to look like bark. Sprinkle extra powdered sugar on top and refrigerate until ready to serve.