Sour Cream Apple Pie with Streusel Topping

I wanted to make an apple pie this year, but I'm always looking for something a little different. This is a first for this recipe, so I'll let you know what everyone thinks!

Filling:
1 cup sour cream
2/3 cup sugar
2 Tablespoons flour
1/4 teaspoon salt
1 teaspoon vanilla
1 egg
3 cups peeled, sliced tart apples (about 1 1/4 pounds of slices)
1 9" unbaked pie shell, frozen or chilled in the freezer for at least 30 minutes (see pâte brisée recipe)

Topping:
1/2 cup brown sugar, packed
1/3 cup flour
1/4 cup butter, room temperature
1/2 teaspoon cinnamon
Mix together all ingredients until the mixture resembes coarse crumbs.

Preheat oven to 400°F.

Beat together sour cream, sugar, flour, salt, vanilla and egg (can beat by hand). Add apples, mixing carefully to coat well.

Put filling into a pie shell and bake at 400 degrees initially for 25 min.

Remove from oven and sprinkle with Cinnamon Crumb Topping. Bake for and additional 20 more minutes.

Let cool for a hour before serving. Serves 8.