Toffee Dessert

1/4 lb. butter
1 cup powdered sugar
3 eggs, separated
1 1/2 squares unsweetened chocolate (melted)
3 oz. chopped nuts
1/4 lb. vanilla wafers

Cream butter with sifted powdered sugar. Beat egg whites until stiff but not dry; set aside. Add egg yolks unbeaten, one at a time, to creamed sugar. Add melted chocolate. Fold in egg whites. Roll wafers into fine crumbs and mix with nuts. Line a buttered square pan half of wafer mixture. Spread chocolate mixture over this, and cover top with remainder of wafer mixture. Refrigerate 5 hours.