Combine fresh blueberries, sugar, and lemon juice in a medium saucepan over medium heat. Gently mash and cook for about 5–7 minutes until juices are released.

Mix cornstarch with a little water to create a slurry. Stir into the blueberry mixture and cook until thickened for about 2 minutes. Remove from heat, cool slightly, and strain if desired.

Preheat your oven to 325°F (160°C).

Combine graham cracker crumbs with melted butter and sugar in a mixing bowl. Line a muffin pan with paper liners and press the mixture firmly into the bottoms of each cavity.

Bake the crusts for 5 minutes. Let them cool completely.

In a large bowl, beat cream cheese and granulated sugar together using an electric mixer until smooth, about 2 minutes.

Gradually incorporate lemon juice, lemon zest, and vanilla extract, mixing just until combined. Add eggs one at a time on low speed, ensuring not to overmix.

Carefully fill each cooled crust with creamy cheesecake filling, leaving a little space at the top.

Spoon a small amount of the blueberry sauce over each cheesecake and gently swirl it into the filling using a toothpick.

Bake for 17-20 minutes until set around the edges but slightly jiggly in the center.

Allow cheesecakes to cool at room temperature for about 1 hour.

Transfer to the refrigerator to chill for at least 3-4 hours or overnight.