Tiramisu Layer Cake

Ingredients
WHITE CAKE:

1 cup (2 sticks) butter, softened
½ cup vegetable shortening
3 cups granulated sugar
5 eggs, room temperature
3 cups all-purpose flour
2 teaspoons baking powder
¼ teaspoon salt
½ cup whole milk, room temperature
½ cup buttermilk, room temperature
2 teaspoons vanilla extract

1 teaspoon instant coffee powder
1/4 cup coffee
1 tablespoon coffee flavored liqueur

FILLING:

1 (8 ounce) container mascarpone cheese
1/2 cup confectioners' sugar
2 tablespoons coffee flavored liqueur

FROSTING:

2 cups heavy cream
1/4 cup confectioners' sugar
2 tablespoons coffee flavored liqueur

GARNISH:

2 tablespoons unsweetened cocoa powder
1 (1 ounce) square semisweet chocolate

Directions

Prepare the white cake.

Preheat oven to 350º F. Prepare three 9-inch round cake pans with nonstick baking spray or coated well with shortening or butter and floured, taking care to remove all excess flour.
Cream together butter and shortening until light and fluffy with an electric mixer. Slowly add sugar one cup at a time, making sure to fully incorporate each cup before adding another. Add eggs one at a time, making sure to fully incorporate each egg before adding another.
Sift together flour, baking powder, and salt. Pour milks and vanilla into measuring cup and whisk together with a fork. Add to butter and shortening mixture alternately with milk mixture, beginning and ending with dry ingredients.
Gently stir all ingredients until well combined. Stop mixer and scrape down sides and bottom of bowl, making sure to have all ingredients mixed well.

 Divide two thirds of batter between 2 pans. Stir instant coffee into remaining batter; pour into remaining pan.
Bake in the preheated oven for 25 to 30 minutes, or until a toothpick inserted into the center of the cake comes out clean. Let cool in pan for 10 minutes, then turn out onto a wire rack and cool completely. In a measuring cup, combine brewed coffee and 1 tablespoon coffee liqueur; set aside.
To make the filling: In a small bowl, using an electric mixer set on low speed, combine mascarpone, 1/2 cup confectioners' sugar and 2 tablespoons coffee liqueur; beat just until smooth. Cover with plastic wrap and refrigerate.
To make the frosting: In a medium bowl, using an electric mixer set on medium-high speed, beat the cream, 1/4 cup confectioners' sugar and 2 tablespoons coffee liqueur until stiff. Fold 1/2 cup of cream mixture into filling mixture.
To assemble the cake: Place one plain cake layer on a serving plate. Using a thin skewer, poke holes in cake, about 1 inch apart. Pour one third of reserved coffee mixture over cake, then spread with half of the filling mixture. Top with coffee-flavored cake layer; poke holes in cake. Pour another third of the coffee mixture over the second layer and spread with the remaining filling. Top with remaining cake layer; poke holes in cake. Pour remaining coffee mixture on top. Spread sides and top of cake with frosting. Place cocoa in a sieve and lightly dust top of cake. Garnish with chocolate curls. Refrigerate at least 30 minutes before serving.
To make the chocolate curls, use a vegetable peeler and run it down the edge of the chocolate bar.