Place fresh blueberries in a saucepan with a splash of lemon juice and granulated sugar over medium heat. Stir occasionally, cooking until the blueberries soften and bubble, about 5-7 minutes.

Whisk cornstarch with a little water and add it to the pan, continuing to cook for another 2-3 minutes until the sauce is thickened.

Strain the sauce if desired, then set aside to cool.

Preheat your oven to 325°F (160°C). Line a muffin pan with cupcake liners.

Combine graham cracker crumbs, sugar, and melted butter in a mixing bowl until fully mixed. Press evenly into the bottom of each cupcake liner.

Bake the crusts for about 5 minutes, then allow them to cool completely.

In a large mixing bowl, beat cream cheese with granulated sugar until smooth and creamy.

Add in lemon juice, lemon zest, and vanilla extract, mixing until well combined.

Add the eggs one at a time, mixing gently after each addition until combined.

Distribute the cheesecake filling evenly among the cooled crusts, filling each liner almost to the top.

Spoon about a teaspoon of blueberry sauce on top of each cheesecake filling and gently swirl.

Bake for 17-20 minutes until the tops are set but still slightly jiggle in the center.

Transfer the cheesecakes to the refrigerator to chill for at least 3-4 hours, or overnight if possible.