Blueberry Sour Cream Pie

1 cup sour cream
2 Tbs flour
3/4 cup sugar
1 tsp vanilla
1/4 tsp salt
1 egg, beaten
2 1/2 cups blueberries
9" graham cracker pie crust

Topping:
3 Tbs flour
2 Tbs margarine
3 Tbs nuts

Preheat oven to 400 °F.

Beat sour cream, flour, sugar, vanilla, salt, and egg until smooth. Fold in blueberries, pour into pie crust. Combine flour, margarine, and nuts to make topping; sprinkle on top of blueberry mixture. Bake for 20-25 minutes, until set. Let cool, then refrigerate until thoroughly cold.