9-inch unbaked pie shell
3 large baking apples (Granny Smith or other), peeled, cored, and
sliced (2-1/2
cups)
3/4 cup sugar
2 tablespoons flour
1 egg, at room temperature
1 teaspoon vanilla
1 cup sour cream, at room temperature
Topping:
1/3 cup flour
1/4 cup butter
1/3 cup brown sugar
1/2 teaspoon cinnamon
 
Preheat oven to 350 degrees. Combine sugar and flour. Add egg, vanilla, and sour cream; beat until smooth. Add apples; mix well. Pour into pie shell; bake 40 minutes. Meanwhile, combine flour, brown sugar, and cinnamon. Cut in butter with a pastry blender or two forks. After pie has baked 40 minutes, remove from oven. Sprinkle topping evenly over pie. Return to oven; bake 20 minutes.