4 tbsp. cornstarch
1/4 tsp. salt
1/3 c. sugar
3 tbsp. cocoa (or 1 sq. chocolate)
2 c. milk
1/2 tsp. vanilla
1 tbsp. butter

Mix together first 4 ingredients. Add 2 cups milk gradually. Cook over medium heat until thick. Add 1/2 teaspoon vanilla and 1 tablespoon butter. Stir and let cool.