1 can (12 oz) evaporated milk
1 bag (12 oz) semisweet chocolate chips (2 cups)
1/2 cup sugar
1 tablespoon butter or margarine
1 teaspoon vanilla
In 2-quart saucepan, heat milk, chocolate chips and sugar to boiling over medium heat, stirring constantly; remove from heat.
Stir in butter and vanilla until sauce is smooth and creamy. Cool about 30 minutes or until sauce begins to thicken. Store covered in refrigerator up to 4 weeks.