For crust/topping: Preheat the oven to 350 degrees.
Line a 9x9 inch baking pan with parchment & give a light spritz with cooking spray.
Combine the flour, sugar, and salt in a medium bowl.
Cut the butter into 1/2-inch cubes, and add to the flour mixture.
Using a fork for pastry cutter, cut the butter in until mixture resembles coarse crumbs.
Remove 3/4 cup of the mixture to use as the topping & set aside.
Press the remaining mixture into the bottom of prepared pan, and bake for 10-12 minutes.
Cool for 10-15 minutes.
For filling: Whisk the eggs in another medium bowl (or just use the one you used for the crust.
Add the granulated and brown sugar, sour cream, flour, salt, butter and vanilla extracts. Whisk well.
Gently fold in the berries and pour the mixture over the crust.
Sprinkle the remaining flour mixture evenly over the filling
Bake 35-45 minutes.
Cool for 1 hour before cutting & serving.