In a large bowl, combine flour, sugar and cocoa; cut in butter until mixture resembles coarse crumbs. Stir in eggs. Set aside 1-1/2 cups for topping. , Press remaining crumb mixture into a greased 13-in. x 9-in. baking pan. Bake at 350° for 6-8 minutes or until set. , Meanwhile, in a saucepan, combine milk and 1 cup of chocolate chips; cook and stir over low heat until melted. Carefully spread over crust. Combine reserved crumb mixture with nuts and remaining chips. Sprinkle over chocolate layer. , Bake for 15-20 minutes or until top is set (chips will not look melted). Cool before cutting.