Mix all dry ingridients together; cream butter and sugar and eggs until nice and creamy. Alternate flour and sour cream. Beat well! Fold in chips. Pour into 13x9 inch greased pan.Mix ingriedients for topping until it is soft streusels. Sprinkle with topping. Bake at 350 degress F for 45-50 minutes.Cool and cut into 24 two inch squares.