Put cookies in container of food processor fitted with metal blade. Process til reduced to fine crumbs. Add 6 Tbsp. melted butter and mix til combined. Press 2 cups of the crumbs over the bottom of a 9 x 13 inch baking pan. Soften ice cream slightly and spread over the cookie layer. Freeze til firm. Meanwhile, melt chocolate and 1/4 lb. butter in medium pan over low heat. Remove form heat and stir in powdered sugar. The mixture will be very stiff. Whisk egg yolks in medium bowl til blended and stir into the chocolate mixture. In a mixing bowl with mixer, beat egg whites til soft peaks form. Fold a dollop into the chocolate mixture to lighten it and then fold in the rest til thoroughly mixed. Spread over the ice cream. Sprinkle the remaining crumbs over the top. Cover with foil and freeze til firm. The dessert may be frozen for several months. to serve, cut into 2 1/2 x 2 1/4 inch squares.