My mother is a great baker, but not big on elaborate directions. I've organized this as best as I can, and it came out quite well when I made it the other morning. Great use for the season's fresh berries. (You could probably do the same with blackberries or raspberries, if you are adventurous).
Preheat the oven to 400 degrees.
Spray 9 inch square pan, and set aside.
For the bottom crust, cream 1 c. softened butter with 1 c. powdered sugar and 1 t. vanilla with a hand held mixer. Add 2 C. flour, and mix just until crumbly Press 3/4 of mixture into bottom of the pan, and bake 12 minutes. Remove from the oven, and reduce the temperature to 350 degrees.
Pour 2 c. blueberries onto crust.
Mix filling:1/2 c. granulated sugar, 3 T. flour, Juice & zest of 1 lemon (or more if you'd like), 1/2 t. salt, and 3 eggs. Pour the filling over blueberries. Spread the balance of the crust mixture on top. Bake 30 to 40 minutes until golden brown.
Cool and cut into squares. This is great for breakfast or snacks, and good as a "not too sweet" dessert, as well.