Combine cake mix, 1 lightly beaten egg, butter or margarine and pecans in a large bowl, stirring until dry ingredients are moistened. Press into bottom of a greased 13 x 9 x 2-inch pan; set aside. Combine cream cheese, vanilla, 2 eggs and 1 cup powdered sugar; beat at medium speed with an electric mixer until blended. Gradually add remaining powdered sugar, beating after each addition. Pour over chocolate layer, spreading evenly. Bake at 350° for 40 minutes. Cool on a wire rack and cut into squares. Yield: 4 dozen.