Preheat oven to 350 degrees
Place flour, sugar, butter and salt in a food processor. Pulse 5-6 times until mixture is crumbly.
Place mixture in a greased 9 x 13 baking dish. Press flour firmly down with hands or the bottom of a flat measuring cup. The mixture will be very dry.
Place in preheated oven for 12 minutes.
Combine sweet and condensed milk, egg yolks, lemon zest and lemon juice.
When crust comes out of the oven, pour blueberries directly over hot crust.
Spoon filling mixture over blueberries. It's okay it it doesn't cover every area.
In another bowl, combine flour, sugar, melted butter and lemon zest. Mix with a spoon, just until the butter is mixed in and then continue mixing with your fingers. You want a crumbly mixture.
Sprinkle crumbles over the top of lemon filling
Bake in 350 degree oven for 40 - 45 minutes. The topping should be browned and the mixture bubbly.
Allow bars to fully cool at room temperature. Then cover with plastic wrap and refrigerate for at least 2 hours.
Slice bars and serve
