Combine butter, flour, and nuts. Mix well and press in 9x13-inch cake pan. Bake 20 minutes at 350°. Let cool.
In medium-sized bowl, combine cream cheese and sugar until fluffy. Fold in 1 cup of whipped topping. Spread over baked crust. Combine chocolate and vanilla puddings with cold milk: beat until thick and creamy. Pour over cheese mixture: top with remaining whipped topping and grated chocolate bar. Chill.