Mascarpone-Frosted Fudge Cake: Line bottom of two greased 8-inch round cake pans with parchment paper; grease paper and flour pan lightly. Whisk butter, water and cocoa in medium saucepan over medium heat until butter is melted and mixture boils. Remove from heat; add chopped chocolate and whisk until melted and smooth. Stir in sugar and cool to room temperature; mix in egg. Combine flour, baking powder and salt in one bowl. In a second bowl, combine buttermilk and vanilla. Mix 1/3 the flour mixture into chocolate mixture; mix in 1/2 the buttermilk mixture. Repeat with remaining flour and buttermilk mixtures, beginning and ending with flour mixture. Pour batter into prepared pans. Bake at 325°F until a toothpick inserted in the center of the cake layers comes out clean, about 20 minutes. Cool on wire rack for 10 minutes. Invert cakes onto rack and remove the parchment paper and cool cake completely. ALMOND TOFFEE: heat butter, corn syrup and sugar in medium saucepan over medium heat, stirring until butter is melted and sugar dissolved. Heat to boiling, stirring constantly; cook until candy thermometer reads 280°F. Stir in almonds and immediately pour onto lightly greased cookie sheet. Cool. Break 1/2 the almond toffee into pieces and process in food processor to make a smooth toffee paste and reserve for Mascarpone Frosting. Crush 1/2 of the remaining almond toffee with meat mallet to make coarse crumbs. Break remaining almond toffee into pieces to garnish cake slices. FROSTING: let mascarpone cheese stand at room temperature in medium bowl until soft enough to stir, 10 to 15 minutes. Stir in toffee paste until smooth. Place 1 cake layer on serving plate and frost with a scant cup cheese mixture; top with second cake layer and frost top and side. Sprinkle top and side of cake with almond toffee crumbs. Garnish cake slices with pieces of Almond Toffee.