Step 1

To make the sponge: Place rack in middle of oven and heat to 350 degrees. Lightly butter four 9x3-inch loaf pans and then line the bottoms with parchment paper. Whip egg whites until stiff. Slowly add 17.5 ounces sugar and again whip to stiff peaks. Mix walnuts with breadcrumbs and gently fold into egg whites until well incorporated. Divide batter evenly among prepared loaf pans and bake about 7 to 12 minutes or until the center springs back when lightly pressed and edges are just beginning to color. Remove from oven and cool in pan 3 minutes.

Step 2

Run a knife around the edge of the sponge cake to loosen it. Carefully invert onto a cooling rack and peel off the parchment paper. Let cool completely. When cool, split each sponge cake in half horizontally so you have 8 layers.

Step 3

To make the filling: Melt chocolate in a microwave and set aside to cool to room temperature. In a large bowl, beat butter on low for 2 minutes, then on medium for 3 minutes and finally on high for 5 minutes. Place egg whites and sugar in a double boiler over medium heat. Whisk gently to 120 degrees. Transfer to a mixing bowl and whip on high until stiff peaks form. Fold the melted chocolate into the whipped butter, then gently fold in the egg whites until all traces of white are gone. Refrigerate until ready to use.

Step 4

To assemble: Place one layer of walnut sponge on a serving tray and spread on a layer of chocolate filling. Repeat until all 8 layers are stacked on top of each other. Frost the top and sides of the torte with the remaining chocolate filling. If desired, garnish with a sprinkle of chopped walnuts but this is not necessary.