SOUR CREAM APPLE PIE

1 3/4 cups all purpose flour

1/4 cup sugar

1 teaspoon cinnamon

1/2 teaspoon salt

1/2 cup plus 2 tablespoons (1 1/4 stick) chilled butter

1/4 cup ice water or cold apple cider 

For filling:

8 McIntosh apples, peeled, cored, and sliced

1 2/3 cups sour cream

1 cup sugar

1/3 cup all purpose flour

1 egg

2 teaspoons vanilla

1/2 teaspoon salt 

For topping:

1 cup chopped walnuts

1/2 cup all purpose flour

1/3 cup firmly packed brown sugar

1/3 cup granulated sugar

1 tablespoon cinnamon

Pinch of salt

1/2 cup (1 stick) butter, room temperature 

To make crust: Combine flour, sugar, cinnamon, and salt in medium bowl. Cut in butter using pastry blender or 2 knives until mixture resembles coarse meal. Add water and toss mixture gently with fork until evenly moistened. Gather gently into ball. Transfer to lightly floured board and roll into circle slightly larger than a deep ten inch pie plate. Ease pastry into pan and flute the edge. Set aside. 

To make filling: Preheat oven to 450F. Combine apples, sour cream, sugar, flour, egg, vanilla, and salt in large bowl and mix well. 

Spoon into crust. Bake 10 minutes. Reduce oven temperature to 350F and continue baking until filling is slightly puffed and golden brown, about 40 minutes. (If edges of crust begin to brown too quickly, cover with strips of aluminum foil.)