Mortgage Cake made with Butterfinger^®

In a mixer with a whip attachment, whip cream at medium high speed until stiff peaks form.  Slice the yellow cake horizontally into three even layers.  Slightly warm the peanut butter sauce in the microwave.  Fold 1/2 cup of peanut butter sauce into the frosting, and fill the cake layers, topping each cake layer with chocolate pieces.  With a cake spatula, ice the cake with a very thin coat of warm peanut butter frosting, leaving the sides slightly exposed. Put in cooler for 1 hour to set. Using a piping bag fitted with a star tip, pipe whipped cream rosettes on top of the cake, top with the remaining chocolate pieces and peanut butter sauce.  Top each whipped cream rosette with one Butterfinger® Mini Bar.