2 c. all purpose flour
2 tsp. baking powder
1 tsp. baking soda
1 tsp. salt
1/2 tsp. ground cinnamon
1/2 c. butter, room temperature
1/2 c. packed brown sugar
1/2 c. sugar
1/3 c. sour cream, room temperature
2 eggs, room temperature
1 tsp. vanilla
1 c. finely chopped unpeeled or peeled tart apples
1 c. toasted finely chopped walnuts

STREUSEL TOPPING:

2 tbsp. cold butter
1/4 c. sugar
3 tbsp. all purpose flour
1/4 tsp. ground cinnamon

Generously grease an 8 x 4 or 9 x 5 loaf pan; set aside. Preheat oven to 350 degrees. Prepare Streusel Topping; set aside. In a large bowl, combine flour, baking powder, baking soda, salt, and cinnamon; set aside. In small bowl, cream butter and both sugars until light. Beat in sour cream, eggs, and vanilla until blended. Fold creamed mixture, apples, and nuts into flour. Turn into prepared pan; smooth top. Sprinkle topping evenly over batter. Bake 50-60 minutes. Let stand 10 minutes.

Streusel Topping: In a small bowl, combine all ingredients. Use pastry cutter to cut in butter until mixture resembled coarse crumbs.