Cream butter and mix in sugar, salt, cocoa, egg yolks, nuts and vanilla.

Beat whites until stiff and fold into mixture. in an 8 x 8 pan, put 1/2 of the cookie crumbs in bottom and pour mixture over top.

Sprinkle the second half of the crumbs on the top.

Refrigerate for at least 24 hours before serving.

Serve with whipped topping.