Chunky Chocolate Peanut Butter Bars Recipe

Preheat oven to 325° and grease a 9x13 pan. Place cake mix, peanut butter, melted butter and eggs in a large mixing bowl. Blend with mixer on low for 1 minute. Stop the machine and scrape down sides of bowl. Reserve 1/2 cup for topping. Transfer remaining mixture to pan. Press mixture evenly over the bottom of the pan. Prepare filling by placing chocolate chips, milk and 2 T. butter in heavy pan over low heat. Stir and cook until chocolate chips are melted and combined, 3-4 minutes. Stir in vanilla. Pour over crust and spread evenly. Crumble reserved peanut butter mixture over chocolate. Bake for 25-30 minutes.