4 1/2 c. sugar
1 pinch cream of tartar
1 can evaporated milk

Cook in heavy pan, stirring constantly. Allow mixture to come to a boil. Boil for 6 minutes (continue stirring). Remove from heat. Add to this mixture: 2 sticks butter 1 1/2 tsp. vanilla

Stir well until smooth and chocolate is dissolved. Pour into greased 9 x 13 inch pan. Cool in refrigerator. Store in refrigerator.