Coffee And Black Walnut Cake With Coffee-Mascarpone Cream - cooking recipe

Ingredients

CAKE
1 cup black walnut, toasted, chopped, divided (about 4 ounces, any kind of walnuts will do)
1 1/4 cups sugar, divided
1 tablespoon instant espresso powder
1 1/3 cups all-purpose flour
1/2 cup cocoa (Dutch process is best)
2 teaspoons baking powder
1/2 teaspoon ground cinnamon
1/4 teaspoon baking soda
1/4 teaspoon salt
10 tablespoons unsalted butter, room temperature
3 large eggs
1 large egg yolk
1/2 teaspoon vanilla extract
3/4 cup buttermilk (add more by teaspoons if needed)
COFFEE-MASCARPONE CREAM
4 1/2 teaspoons instant espresso powder
1/4 teaspoon cinnamon
1 tablespoon water
1 cup chilled heavy whipping cream
1/2 cup mascarpone cheese
1/2 cup powdered sugar
1/2 teaspoon vanilla extract
3/4 cup about 3 ounces black walnut, toasted, chopped
1/4 teaspoon ground cinnamon
1 pinch salt

Preparation

For cake:
Position rack in center of oven and preheat to 350\u00b0F.
Butter and flour two 9-inch-diameter cake pans with 1 1/2-inch-high sides.
Blend 1/2 cup walnuts, 1 tablespoon sugar, and espresso in processor until nuts are finely ground.
Whisk flour, cocoa, baking powder, cinnamon, baking soda, and salt in medium bowl to blend. Using electric mixer, beat butter in large bowl until smooth.
Gradually add remaining sugar (1 1/4 cups minus 1 tablespoon), beating until fluffy. Beat in eggs, 1 at a time, then egg yolk. Add ground walnut mixture and vanilla; beat to blend.
Reduce mixer speed to low and beat in dry ingredients in 3 additions alternately with buttermilk in 2 additions.
Fold in remaining 1/2 cup walnuts.
Divide batter evenly between prepared pans.
Bake cake layers until tester inserted into center comes out clean, about 26 minutes. Cool in pans 5 minutes, then turn out onto racks and cool completely.
For coffee-mascarpone cream:
Stir espresso, cinnamon and 1 tablespoon water in large bowl until coffee dissolves.
Add cream, mascarpone, sugar, and vanilla. Beat until filling is thick and smooth (do not overbeat or filling may curdle).
Place 1 cake layer on platter, flat side up. Spread half of filling over cake.
Place second layer, flat side down, on filling.
Spread remaining filling over top. Mix walnuts, cinnamon, and salt.
Sprinkle over top of cake.
Cover with cake dome.
Chill at least 1 hour and up to 1 day.