In the bowl of your mixer, dump in flour, sugar, butter and salt. Beat with the paddle attachment for a couple of minutes until the dough comes together in small chunks.
Press half of the dough into the bottom of a greased 9 x 9 pan. Set aside the remaining dough.
Bake the dough for 10 minutes. Let cool for 10 minutes.
For the filling:
Whisk the eggs in a large bowl. Add sugar, sour cream and flour to the eggs. Mix well and then fold blueberries.
Pour blueberry mixture over baked crust and spread evenly.
Use your hands to squeeze together chunks of the reserved dough. Sprinkle on top of the blueberry mixture and bake for 50-60 minutes.
Let cool one hour before serving.
Notes
I have not tested this recipe with frozen blueberries, but it should work fine.