In a bowl, combine the cake mix, eggs and extract. Add pie filling; mix well. Spread into a greased 15x10x1-in. baking pan. Bake at 350° for 18-22 minutes or until a toothpick inserted in the center comes out clean.
Meanwhile, in a saucepan, combine sugar, milk and butter. Cook and stir until sugar is dissolved and butter is melted. Remove from the heat; stir in chocolate chips until melted. Pour over warm cake; spread evenly. Cool completely before cutting. Store in the refrigerator.