Heat oven to 350 °F. Grease and floured a 9-in. bread pan; set aside. In a mixing bowl, cream sugar and butter well. Add eggs, one at a time, beating well after each addition. Add flour, baking powder, baking soda and salt to creamed mixture, beating at low speed until blended. Then stir apples, nuts, vanilla extract and sour cream into batter. Pour batter into pan. For topping, combine flour, sugar, cinnamon and nuts; cut in butter until crumbly. Sprinkle over batter. Bake at 350 °F for 60 minutes or until a wooden pick inserted near the center comes out clean. Cool in pan on a wire rack for 15 minutes; remove from pan. Serve warm.