Make the Blueberry Swirl – In a saucepan over medium heat, combine blueberries, sugar, and lemon juice. Cook until the berries soften, mashing as they cook.
Once bubbling, whisk water and cornstarch together, then add to the saucepan. Cook for 1-2 more minutes, stirring until thickened. Strain through a fine-mesh sieve, discarding solids. Set aside to cool.

Make the Crust – Preheat oven to 325°F (163°C). Line 14 muffin tins with cupcake liners.
In a bowl, mix graham cracker crumbs, sugar, and melted butter until combined. Press the mixture into the muffin tins. Bake for 5 minutes, then set aside to cool.

Make the Cheesecake Filling – Beat the cream cheese and sugar until smooth. Mix in lemon juice, lemon zest, and vanilla extract.
Add eggs one at a time, mixing on low speed until just combined.

Assemble the Cheesecakes – Divide the filling between the muffin tins. Top each cheesecake with about 1 teaspoon of blueberry swirl, and use a toothpick to create a swirl pattern.

Bake – Bake at 325°F for 17-20 minutes, or until the tops are set. Let cool at room temperature for 1 hour.

Chill – Transfer to an airtight container and refrigerate for at least 3-4 hours, or overnight before serving.