Follow these detailed steps carefully to ensure your mini cheesecake bites turn out perfectly every time. The key is patience, especially during the mixing and cooling stages.

Step 1: Preparation

• Preheat your oven to 325°F (163°C).
• Line a standard 12-cup muffin tin with paper liners. This is highly recommended for easy removal. If you have a 24-cup mini muffin tin, you can use that for even smaller, one-bite treats, but you will need to adjust the baking time down significantly (check after 15 minutes).

Step 2: Make the Graham Cracker Crust

• In a medium bowl, combine the graham cracker crumbs and the ¼ cup of granulated sugar.
• Pour the 6 tablespoons of melted unsalted butter over the crumb mixture.
• Stir with a fork until all the crumbs are evenly moistened. The mixture should resemble wet sand.
• Distribute the crumb mixture evenly among the 12 muffin liners, adding about 1 ½ tablespoons to each.
• Use the bottom of a small glass, a spice jar, or your fingers to firmly press the crumbs down into a flat, compact layer.
• Bake the crusts for 5-7 minutes, just until they are set and fragrant. Remove from the oven and set the pan aside to cool while you prepare the filling.

Step 3: Prepare the Blueberry Swirl Topping

• In a small saucepan, combine the blueberries, 2 tablespoons of sugar, and 1 tablespoon of lemon juice.
• Cook over medium heat, stirring occasionally, until the blueberries begin to burst and the mixture starts to bubble and thicken, about 5-8 minutes.
• In a separate small bowl, whisk together the 1 tablespoon of cornstarch and 1 tablespoon of cold water until a smooth slurry forms with no lumps.
• Pour the cornstarch slurry into the simmering blueberry mixture, stirring constantly.
• Continue to cook for another 1-2 minutes, stirring, until the sauce has noticeably thickened to a jam-like consistency.
• Remove the saucepan from the heat and set it aside to cool completely. For a smoother swirl, you can strain the mixture through a fine-mesh sieve to remove the blueberry skins, but this is optional.

Step 4: Create the Cheesecake Filling

• In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, beat the softened cream cheese on medium-low speed until it is completely smooth and creamy, with no lumps. This is a critical step; take your time and scrape down the sides and bottom of the bowl frequently.
• With the mixer still on low, gradually add the ¾ cup of granulated sugar and the 1 tablespoon of flour. Mix until just combined, scraping the bowl again to ensure everything is incorporated.
• Add the room-temperature eggs one at a time, mixing on low speed until the yolk is just broken and incorporated after each addition. Do not overmix! Overmixing incorporates too much air, which is the primary cause of cracks in cheesecake.
• Finally, stir in the sour cream (or Greek yogurt), vanilla extract, and lemon zest on low speed until just blended. Give the bowl one final scrape and a gentle fold with a spatula to ensure the batter is uniform. The final batter should be thick, smooth, and velvety.

Step 5: Assemble and Swirl the Cheesecakes

• Spoon or pour the cheesecake filling evenly over the pre-baked crusts in the muffin tin, filling each liner about ¾ of the way full.
• Drop small dollops of the cooled blueberry topping onto the surface of each cheesecake filling. Aim for 3-4 small drops per cheesecake.
• Take a toothpick or a thin skewer and gently drag it through the blueberry dollops and cheesecake filling to create a beautiful marbled or swirl pattern. Don’t overdo it; a few simple passes are all you need for an elegant look.

Step 6: Bake the Mini Cheesecakes

• Place the muffin tin on the center rack of your preheated 325°F (163°C) oven.
• Bake for 18-22 minutes. The cheesecakes are done when the edges are set and the centers are almost set but still have a very slight jiggle to them when the pan is gently shaken. They will continue to set as they cool. Over-baking will lead to a dry texture and cracks.

Step 7: The Crucial Cooling Process

• Turn off the oven, but do not remove the cheesecakes. Prop the oven door open with a wooden spoon and let the cheesecakes cool in the slowly cooling oven for 1 hour. This gradual temperature change is another key step in preventing cracks.
• After an hour, remove the muffin tin from the oven and let it cool on a wire rack at room temperature for another hour.
• Once cooled, cover the tin with plastic wrap and transfer it to the refrigerator to chill for at least 4 hours, but preferably overnight. This chilling period is essential for the cheesecake to fully set and for the flavors to meld and develop. Do not rush this step!