My favorite apple pie. I love the way the fresh apples taste layered in thin slices, rather than premade into a syrupy filling. The sour cream and walnut topping compliment this perfectly. You are welcome to peel the apples as you wish, but I do not cleanly peel the apples, leaving a little bit of peel here and there. I like the added texture, flavor, and nutrients.
Prepare streusel: Combine flour, brown sugar, cinnamon and salt. Stir in walnuts. Add butter and vanilla and lightly stir with a fork until evenly moist. Set aside.
Prepare Sour Cream topping: In small bowl, combine sour cream and white sugar. Cover and refrigerate.
Layer the apple slices in the pie shell very tightly and densely, without gaps. Spread the sour cream mixture over the apples leaving a half-inch border at the edge. Cover with streusel all the way to the edge.
Cover edge of piecrust with foil to avoid overbrowning. Place on a cookie sheet and bake for 10 minutes. Reduce temperature to 350 degrees F. Bake about 45 minutes or until topping is browned and pie is bubbling.