• Make the blueberry compote. In a medium saucepan, add the blueberries, sugar, lemon zest, and lemon juice and bring to a gentle simmer over medium-low heat. Stir gently so that the blueberries release their juices and simmer for about 8-10 minutes, until slightly thickened. Mix the cornstarch with 1 tablespoon cold water, then add to the blueberries and simmer for another 2-3 minutes, until very thick. Cool completely. This can be done up to 3 days in advance and stored in the fridge.
• Preheat an oven to 350 F. Grease and line an 8x8 metal baking pan with parchment paper so that there’s overhang over two sides. This makes extracting the bars from the pan much easier.
• Make the crust/crumble. Using a hand mixer, beat the butter and sugars together in a mixing bowl until light and fluffy, about 2 minutes or so. Add the flour and salt and mix on low speed until the mixture is clumping together in small crumbles. Spread about 2/3 of the crumble in the prepared baking pan and use a small measuring cup to press into an even layer across the bottom. Transfer the rest of the crumble to the fridge. Bake for 10 minutes, then cool to room temperature.
• Reduce the oven temperature to 325 F.
• Make the cheesecake filling. In a mixing bowl, beat the cream cheese and sugar together until smooth. Then, beat in the eggs, one a time, until well incorporated. Finally, fold in the sour cream and vanilla bean paste until totally smooth.
• Layer the bars. Spoon about 2/3 of the blueberry compote over the cooled crust. Pour the cheesecake filling over the top and use an offset spatula to make sure it’s in an even layer. Dollop the remaining blueberry compote over the top and use a knife to make a couple swirls. Top with the remaining crumble mixture from the fridge.
• Bake for 30 minutes. Then, lower the oven temperature to 300 F and bake for another 30-35 minutes, until the center of the bars just barely jiggles. Cool the bars to room temperature, then refrigerate for 4 hours, or overnight.
• Run a knife around the edge of the bars to loosen them, then use the parchment overhang to pull the bars from the pan. Use a knife heated with hot water to make clean slices and cut the bars into 9 or 16 pieces.

Make Ahead & Storage Instructions

• Make ahead: The blueberry compote can be made up to 3 days in advance and stored in the fridge in an airtight container. The cheesecake bars can be made several days in advance and stored in the fridge covered with plastic wrap.

  To freeze: Wrap the uncut cheesecake bars really well in plastic wrap and then place them in a freezer safe ziplock bag (this helps prevent freezer burn). Freeze for up to 3 months. Defrost overnight in the fridge.