Place the blueberries, sugar, and Meyer lemon juice in a small saucepan over medium heat. Warm until the berries soften and start releasing their liquid, gently pressing them with a spoon as they cook.

When the mixture begins to bubble steadily, whisk the cornstarch into the water in a tiny bowl until smooth. Pour this slurry into the pan and keep mashing and stirring for 1 to 2 minutes, until the sauce visibly thickens.

Take the pan off the heat, set a fine-mesh sieve over a heatproof bowl, and pour the blueberry mixture through the sieve. Press on the solids to extract as much sauce as possible, then discard the skins and let the blueberry sauce cool completely.

Preheat the oven to 325°F. Fit 14 standard muffin cups with paper liners across one or two muffin tins.

In a mixing bowl, combine the graham cracker crumbs, sugar, and melted butter. Stir with a fork until every crumb is moistened.

Spoon the crumb mixture evenly into the 14 lined wells, pressing each portion firmly into an even layer. Bake for 5 minutes, then remove the pan(s) to a wire rack to cool. Keep the oven at 325°F.

In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl using a hand mixer, beat the softened cream cheese and sugar together until completely smooth and fluffy.

Mix in the Meyer lemon juice, lemon zest, and vanilla extract, stopping to scrape down the sides of the bowl once or twice. Add the eggs one at a time, mixing on low speed after each addition just until the yolk disappears.

Divide the cheesecake filling equally among the 14 prepared crusts. Drop about 1 teaspoon of the cooled blueberry sauce onto each and drag a toothpick or the tip of a knife through the surface to create marbled swirls.

Bake at 325°F for 17 to 20 minutes, or until the tops look set and barely jiggle in the center. If you used two pans, bake them on separate oven racks or in batches.

Let the cheesecakes cool on the counter for at least 1 hour.

Once cool, lift the cheesecakes out of the muffin tin and transfer to an airtight container. Refrigerate for 3 to 4 hours or overnight to fully set, then serve chilled.