1 c. cocoa
1/2 c. sugar
2 (14 oz.) cans sweetened condensed milk
1 c. butter
1 c. coarsely chopped walnuts
1 1/2 tsp. vanilla

Combine cocoa and sugar in a 4 quart saucepan. Blend in condensed milk. Add butter; cook, stirring constantly over medium heat until mixture boils and becomes very thick. Boil and stir 10 minutes. Remove from heat. Blend in nuts and vanilla. Spread mixture evenly in a foil lined 9"x9" pan. Chill 2 hours or until firm. Cut into 1" squares. Store in air tight container.