Line a 9×5-inch loaf pan with foil for easier cleanup and slicing ability (you can pick the whole thing up and place on a cutting board) and spray with cooking spray; set aside.
Slice the pound cake in half lengthwise (two large slabs) and place the bottom half in the prepared pan; set the top half aside.
To a large glass measuring cup, add the brewed espresso, coffee liquor, stir to combine, and drizzle half the mixture over the cake layer in the prepared pan; set aside.
To a large bowl, add the mascarpone cheese, confectioners’ sugar, heavy cream, and beat with a handheld electric mixer on high speed for about 4 to 5 minutes or until quite stiff.
Evenly spread about half of the cream mixture over the cake layer in the pan, about 1 1/2 cups. Note – I don’t mind having this layer be very thick and some will inevitably ‘leak’ out the sides when you add the top layer of the cake but if you prefer less filling, add it to taste.
To the remaining cake layer (top layer), poke holes in it with a fork in about 30 spots to help the coffee mixture soak in easier.
Add the top layer over the cream layer.
Slowly and evenly drizzle with the remaining coffee mixture. It’s okay if it all doesn’t fully absorb into the top and pools down the sides; it will absorb into the bottom layer.
Evenly spread about 1 1/2 cups of the remaining cream mixture over the top, or as desired.
Chill the tiramisu for about 3 hours and just prior to slicing and serving, evenly dust with the cocoa powder.