Heat oven to 350 degrees. ... 13"x9" pan. Prepare cake batter according to package directions ... Sprinkle 3/4 cup chocolate chips over batter. Gently spread remaining ... clean. Cool in pan.
Combine crumbs, sugar, and butter; ... addition. Blend in chocolate chips and vanilla; pour over crust. ... 35 minutes. Loosen cake from rim of pan; cool ... Chill. Makes 10-12 servings.