1. Preheat oven to 400°F.
2. Crust:
3. In the bowl of your food processor place the flour and sugar. Pulse to blend together. Add butter and pulse until dough just begins to come together. Pat the dough onto the bottom and one inch (2.5 cm) up the sides of the pan. Cover with plastic wrap and place in refrigerator while you make the filling.
4. Beat together sour cream(yogurt), sugar, flour, salt, vanilla and egg (can beat by hand). Add apples, mixing carefully to coat well.
5. Put filling into a pie shell and bake at 400 degrees initially for 25 min.
6. Remove from oven and sprinkle with Cinnamon Crumb Topping. Bake for and additional 20 more minutes.