Step 1

Preheat oven to 375 degrees Fahrenheit. In a large bowl, whisk the sour cream, sugar, flour, salt, egg, and vanilla.

Step 2

Stir in sliced apples. Pour into two pie crusts. Bake for 20 minutes.

Step 3

Reduce oven to 350 degrees Fahrenheit and bake for 35 minutes longer.

Step 4

Combine the walnuts, flour, sugar, brown sugar, cinnamon, and salt. Stir in melted butter and mix until crumb forms.

Step 5

Sprinkle the topping over the two pies and bake for an additional 30 to 35 minutes until golden.

Step 6

Cool at room temperature for several hours before serving.