Reese's Peanut Butter Cup Cake

1 cup unsalted roasted peanuts
3/4 cup flour
6 eggs
2 egg yolks
1 cup firmly packed light brown sugar
1 teaspoon vanilla extract
1/2 cup creamy peanut butter
1/2 cup butter
5 tablespoons confectioners' sugar
1/2 cup whipping cream
5 Reese's Peanut Butter cups - finely chopped (1.8 ounces)
1 1/2 cups chilled whipping cream
3 tablespoons light brown sugar
1/2 cup unsalted roasted peanuts, coarsely chopped
3 Butterfinger bars - cut into 3/4 inch wedges (2.1 ounces)
1/2 cup Reese's Pieces

Heat the oven to 375 degrees F. Butter and flour two 9 x 2 inch round cake pans.

Grind the nuts and 3/4 cup of flour in a food processor until fine.

Using a mixer, beat eggs, yolks, sugar and vanilla extract in a large bowl until the mixture whitens and triples in volume. Fold in the nut mixture. Divide the batter between the prepared pans and smooth the tops.

Bake until a wooden pick inserted in the center comes out clean, or about 20 minutes.

Cool the cakes in the pans on rack.

For the filling, blend peanut butter, butter and sugar in a processor until smooth. With the machine running, add the cream through the feed tube and blend until the mixture is light and fluffy.

Invert the cakes onto a work surface. Using a serrated knife, cut each cake into 2 layers. Place 1 cake layer on a platter, cut side up.

Spread with 1/3 of the filling and sprinkle with 1/3 of the chopped peanut butter cups. Top with a second cake layer, cut side down. Continue layering with the remaining filling, peanut butter cups and cake, ending with the cake, cut side down.

For the topping, beat the cream, sugar and vanilla in large bowl until almost stiff.

Transfer 1/2 cup to a small bowl and reserve for garnish.

Spread the remaining whipped cream over the top and the sides of the cake. Press nuts around the base of the cake forming a 1 1/2 inch high border. Cover the top of the cake with Butterfingers leaving a 1/2-inch border.

Spoon the reserved whipped cream into a pastry bag fitted with a medium star tip; pipe stars around the top edge.

Garnish with Reese's Pieces.