Sour cream apple pie

---------- Recipe via Meal-Master (tm) v8.03
  
       Title: SOUR CREAM APPLE PIE
  Categories: Desserts, Pies, Fruits/nuts
       Yield: 6 servings
  
 ----------------------------PIE----------------------------
            9-inch deep-dish pie shell
       1 c  Sour cream
            Large egg, lightly beaten
       2 ts Pure vanilla extract
     3/4 c  Sugar
     1/8 ts Salt
     1/4 c  All-purpose flour
       2 lb Granny Smith apples *
 
 --------------------------TOPPING--------------------------
     1/3 c  All-purpose flour
     1/4 c  Sugar
     1/4 c  Light brown sugar, packed
   2 1/2 ts Cinnamon, ground
     3/4 c  Walnuts, chopped
       6 tb Butter, unsalted **
  
   *   peeled, cored, and thinly sliced
   **  chilled and cut into pieces
   In large bowl, combine sour cream, egg, vanilla,
   sugar, salt, and flour, stirring until well blended.
   Stir in apples.  Pour into unbaked pastry shell.  Bake
   at 425 degrees for 10 minutes.  Reduce heat to 350 and
   bake an additional 30 minutes.
   TOPPING:
   Combine all topping ingredients, blending until
   mixture resembles coarse meal.  Spoon topping over pie
   and bake at 350 minutes for an additional 15 to 20
   minutes, or until filling is bubbly.
     -- from CREME DE COLORADO cookbook
  
 -----