1 3/4 cups all-purpose flour
1/4 cup sugar
1 teaspoon cinnamon
1/2 teaspoon salt
1/2 cup plus 2 tablespoons butter
1/4 cup water or apple cider
1 2/3 cups sour cream
1 cup sugar
1/3 cup all-purpose flour
1 egg
2 teaspoons vanilla
1/2 teaspoon salt
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 salt
1/2 cup butter, room temperature
METHOD:
For crust:
Combine flour, sugar, cinnamon, and salt in a medium bowl. Cut in butter using a pastry blender or two knives until the mixture resembles a coarse meal. Add water and toss the mixture gently with a fork until evenly moistened. Gather gently into a ball. Transfer to a lightly floured board and roll into a circle slightly larger than a deep 10-inch pie plate. Ease pastry into pan and flute high edge. Set aside.
For filling:
Preheat oven to 450 degrees F. Combine all ingredients in a large bowl and mix well. Spoon into prepared crust. Bake for 10 minutes. Reduce oven temperature and bake until puffed and golden brown, about 40 minutes. If the edges of the crust begin to brown too quickly, cover them with strips of aluminum foil.
For topping:
Meanwhile, combine walnuts, flour, sugars, cinnamon, and salt in a medium bowl and mix well. Blend in butter until the mixture is crumbly. Spoon over pie and bake 15 minutes longer.