1 (12 oz.) pkg. semi-sweet chocolate chips
1/2 c. butter
2 c. graham cracker crumbs
1 (8 oz.) cream cheese
1 (14 oz.) can sweetened condensed milk
1 egg
1 tsp. vanilla extract

Melt chocolate chips and butter in medium saucepan over very low heat, stirring constantly until smooth. Stir in graham cracker crumbs. Remove 1/4 cup of mixture to use later. Press remaining crumb mixture evenly and solidly in 13x9 baking dish.

In large bowl (using electric mixer) beat cream cheese until smooth. Gradually beat in condensed milk, egg, and vanilla (each separately). Pour over prepared crust. Sprinkle with reserved 1/4 cup crumb mixture.

Bake in 325 degree oven about 25 minutes, or until firmly set. Cool. Refrigerate about 3 hours until very cold. Cut in diagonal lines to form diamonds.