Cook the blueberries, sugar and lemon juice in a small saucepan over medium heat for about 5 minutes, until the berries burst. Stir the cornstarch into the water, add it to the pan and simmer for 1 minute until thick, then let the sauce cool completely.
Preheat the oven to 325°F, place a pan of hot water on the lower rack and line a 12-cup muffin pan with paper liners. Mix the graham cracker crumbs, sugar and melted butter, press 1 heaping tablespoon into each liner and bake for 5 minutes.
Blend the cottage cheese in a food processor or blender for 2 to 3 minutes, scraping down the sides, until completely silky.
Add the cream cheese, sugar, cornstarch, vanilla and lemon zest and blend until smooth. Add the eggs and pulse just until combined.
Divide the filling among the liners, filling each almost to the top. Drop 1 teaspoon of blueberry sauce onto each one and swirl it gently with a toothpick.
Bake for 20 to 23 minutes, until the edges are set and the centers wobble slightly. Turn off the oven, crack the door and let them cool inside for 15 minutes.
Cool completely at room temperature, then refrigerate for at least 4 hours. Spoon the remaining blueberry sauce over the tops just before serving.