Instructions

1. Preheat oven to 350 degrees. For the ease of removal and cleanup, line a 9″ x 13″ baking pan with aluminum foil and then spritz with non-stick cooking spray.
2. For the shortbread crust and crumble, melt the butter in a large microwave safe bowl for about 1 minute or melt butter in a large pot on the stove and remove from heat.
3. Mix in sugars, stirring well to combine.
4. Add in flour and salt and mix well. The mixture will be dry and crumbly.
5. Scoop out 1-1/2 cups of the mix and set aside to use for the crumble later.
6. Pour the remaining shortbread mixture into the prepared pan and press down firmly with your hands or a spatula to create a even, flat crust on the bottom of the pan. Set aside.
7. For the filling, whisk together eggs, sour cream, sugar, and vanilla in a medium bowl.
8. Add flour and mix well.
9. Pour filling evenly over the crust and smooth lightly with a spatula. Set aside.
10. For the blueberry layer, combine blueberries, sugar, lemon juice, and cornstarch in a medium bowl and toss to combine.
11. Distribute blueberry mix evenly over the filling layer in the pan.
12. Sprinkle reserved shortbread crumble evenly over the blueberries, using your hands to squeeze the crumble to form some larger clumps.
13. Bake for about 70 minutes or until bubbling and the crumb topping is a light golden color.
14. Allow bars to cool on a wire rack for several hours up to overnight to allow for easier slicing and serving.