The perfect shortbread crust, creamy custard, and loaded with blueberries.
Preheat oven to 350 degrees.
Beat eggs until combined, then add the sugar and beat until foamy. Add the sour cream, 1/2 cup flour, cornstarch and salt and beat until incorporated. Stir in vanilla and lemon zest.
Add blueberries to a bowl, sprinkle with the 2 tablespoons flour and toss to coat. Add the blueberries to a sieve and shake out excess flour. Fold into the egg/sugar mixture.
Pour over the top of the shortbread crust, using a spatula to smooth as necessary.
Place in oven and bake for about 30 – 35 minutes. Bars are done when the center is just set. Let cool to room temperature and then refrigerate.