Preheat oven to 325 degrees
Start by making the shortbread crust. To a food processor add the flour, sugar, cornstarch and salt. Pulse several times.
Add cold diced butter and vanilla to the processor. Process until the dough starts to come together but is still crumbly -- about 60 seconds.
Add the dough to a parchment lined 9x9 pan. Evenly distribute the crust and press it into the bottom of the pan until it all sticks together.
Bake in the middle rack for 20 minutes.
While the crust bakes make the rest of the components starting with the crumble topping. Add brown sugar, sugar, melted salted butter, flour, cinnamon and salt to a mixing bowl. Mix with a fork until fully combined and crumbly. It will resemble wet sand. Place in the refrigerator.
For the blueberry layer, add fresh blueberries, sugar, cornstarch and lemon juice to a medium pot set over medium and cook for 7 minutes. Stir often and smash berries with a wooden spoon if you like more of a jammy consistency to your blueberry layer. Once done cooking stir in the vanilla, mix and set aside.
For the cheesecake layer, add softened cream cheese and sugar to a mixing bowl or stand mixer, blend until combined. Add egg, lemon juice and vanilla and continue beating until smooth.
To assemble, add cheesecake layer directly onto the cooked shortbread crust, spread out then top with the blueberry layer and spread out once more. Remove crumble topping from the refrigerator and break up with a fork. You want the crumbles to range in size from sand to small marbles. Spread all the crumble topping on top of the blueberry layer.
Increase oven temperature to 350 degrees and bake the bars in the middle rack for 45 minutes.
Remove from the oven and cool to room temperture then place in the refrigerator overnight (or 8+ hours). Cut and serve cold. Store in the refrigerator.