3 (6 oz.) pkg. chocolate chips
1/3 c. butter
3 tbsp. vanilla
1 c. walnuts (optional)
4 1/2 c. white sugar
1 can evaporated milk (1 2/3 c.)

Mix chips, butter, and vanilla in large bowl. In large heavy pan heat to boil and cook exactly 6 minutes 4 1/2 cups sugar and evaporated milk. Pour the sugar and milk over chip mixture, stir until chips are melted; add nuts if desired. Pour into 9 x 13 inch pan. Allow to set several hours.