Classic! This is one of my absolute favorite cakes. I love the rich, smooth and satisfying flavors of the walnuts, butter, coffee, and vanilla.
- To make the sponge: Place rack in middle of oven and heat to 350 degrees. Lightly butter four 9-inch round pans and then line the bottoms with parchment paper. In a large bowl or stand mixer, whip egg whites until stiff. Slowly add 3/4 cup granulated sugar and again whip to stiff peaks. Mix walnuts with whole-wheat flour and gently fold into egg whites until well incorporated. Divide batter evenly among prepared pans. (If you only have two 9-inch round pans, use those and just split the cake in half after baking and cooling, so you have four layers). 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. Brush lightly with milk to add additional moisture. Cool in pan for 3 minutes. Then invert onto wire rack to cool completely.
- To make the buttercream: Fill a medium saucepan with about 1 inch of water and set it to simmer. Meanwhile, in a stand mixer or metal bowl, beat the 15 egg yolks with 2 cups confectioners’ sugar on medium-high speed for about 6 to 7 minutes or until thick and lemony. Place bowl over (NOT IN) simmering water and whisk constantly for 15 minutes. Be careful that the yolks don’t scramble. Add instant coffee and mix. Let cool to room temperature.
- Next step: In a separate bowl, whip together butter and vanilla and fold into the cooled egg yolk-sugar-coffee mixture.
- To assemble: Place one layer of sponge cake on a cake platter and spread a layer of coffee buttercream on top. Repeat until all layers are stacked on top of each other. Frost the top and sides of the torte with the remaining buttercream. Not necessary, but if desired, garnish with a sprinkle of chopped walnuts. Store refrigerated.