Preheat oven to 400 degrees.
Peel core and thinly slice approximately 4 Granny Smith apples and 2 Red Delicious apples. Set inside a bowl of water with lemon juice to keep them for browning.
Beat together with mixer 1 cup sour cream, 2/3 cup sugar, 2 tablespoons flour, 1/2 teaspoon kosher salt, 1 teaspoon vanilla, 1 large egg.
Pat the apples dry on towel to rid the excesss water, and add the apples to the sour cream mixture, and coat well. (DO NOT USE MIXER! ;)
Put filling into a pie shell and bake for 25 minutes.
While Pie filling is cooking up, mix together 1/2 cup brown sugar, 1/3 cup flour, 1/4 cup room temperature butter, 1/2 teaspoon of cinnamon. Crumble together with your hands to make sure it combines well. Remove pie from oven and sprinkle the streusel topping on top of the pie. Bake for an additional 20 minutes.
Let cool so it's not piping hot, but best served warm.
Everyone loved it this weekend!