1. Preheat oven to 350°. Beat butter and shortening at medium speed with an electric mixer until fluffy; gradually add sugar, beating well.
2. Stir together milk and 2/3 cup water. Combine flour and next 2 ingredients; add to butter mixture alternately with milk mixture, beginning and ending with flour mixture. Beat at low speed just until blended after each addition. Stir in vanilla bean paste and almond extract.
3. Beat egg whites at high speed until stiff peaks form, and fold into batter. Spoon batter into 3 greased and floured 8-inch round cake pans.
4. Bake at 350° for 25 to 30 minutes or until a wooden pick inserted in center comes out clean. Cool in pans on wire racks 10 minutes; remove from pans to wire racks, and cool completely (about 1 hour).
5. Meanwhile, prepare Coffee Syrup.
6. Prepare Mascarpone Frosting. Pierce cake layers with a wooden pick, making holes 1 inch apart. Brush or spoon coffee Syrup over layers.
7. Place 1 cake layer, brushed side up, on a cake stand or serving plate. Spread top with 1 1/3 cups Mascarpone Frosting. Top with second cake layer, brushed side up, and spread with 1 1/3 cups Mascarpone Frosting. Top with remaining cake layer, brushed side up. Spread top and sides of cake with remaining Mascarpone Frosting. Chill 4 hours before serving. Garnish, if desired.