Step #2 Prepare the cake mix according to package directions.
Step #3 Divide two thirds of batter between 2 pans.
Step #4 Stir instant coffee into remaining batter; pour this into remaining pan.
Step #5 Bake in the preheated oven for 20-25 mins, or until a toothpick inserted into the center of the cake comes out clean.
Step #6 Let cool in pan for 10 mins, then turn out onto a wire rack & cool completely.
Step #7 In a measuring c, mix brewed coffee & 3 tbsps Kahlua; set aside.
Step #8 To make the filling: In a small bowl, mix mascarpone, using an electric mixer set on lowish speed, 1/2 c powdered sugar & 2 tbsps Kahlua; beat just until smooth.
Step #9 Cover up with plastic wrap & put in the fridge.
Step #10 To make the frosting: In a medium bowl, beat the cream, using an electric mixer set on medium-high speed, 1/4 c powdered sugar & 2 tbsps Kahlua until stiff.
Step #11 Fold 1/2 c of cream mixture into filling mixture.
Step #12 To assemble the cake: Place one plain cake layer on a serving plate.
Step #13 Using a thin skewer, poke holes in cake, about 1 inch apart.
Step #14 Spoon one third of reserved coffee mixture over cake, then spread with half of the filling mixture.
Step #15 Top with coffee-flavored cake layer; poke holes in cake.
Step #16 Spoon another third of the coffee mixture over the second layer & spread with the remaining filling.
Step #17 Top with remaining cake layer; poke holes in cake.
Step #18 Spoon remaining coffee mixture on top.
Step #19 Spread sides & top of cake with frosting.
Step #20 Place cocoa in a sieve & lightly dust top of cake.
Step #21 Garnish with chocolate curls.
Step #22 Refrigerate at least 30 mins before serving.
Step #23 To make the chocolate curls, use a vegetable peeler & run it down the edge of the chocolate bar.