Line three 3-qt. metal bowls with plastic wrap; set aside. Combine 3 qt. of the OREO Pieces and the butter; mix well. Press 2 cups of the OREO Piece mixture firmly onto bottom and up side of each bowl. Freeze 1 hour. Set remaining OREO Piece mixture aside for later use.
Arrange 4 cake slices, side-by-side, on bottom of each bowl. Drizzle each with 2 Tbsp. of the créme de cocoa. Cover each with layers of 2 cups of the raspberry sorbet, 3 Tbsp. of the butterscotch sauce and 3/4 cup of the remaining OREO Pieces. Freeze at least 1 hour. Cover each with 2 cups of the vanilla ice cream, 3 Tbsp. of the butterscotch topping and 1-1/4 cups of the remaining OREO Pieces. Return to freezer for at least 1 hour.
Top each with layers of 2 cups each of the chocolate ice cream and remaining OREO Piece mixture; drizzle each with 2 Tbsp. of the remaining créme de cocoa. Cover tightly with plastic wrap. Freeze several hours or overnight.
Remove top sheet of plastic wrap from each bowl just before serving. Invert bowl onto cutting board; remove remaining plastic wrap. Using knife dipped in hot water, cut each dessert into 12 wedges to serve.