Preheat the oven to 325°F. Line a 12-cup muffin tin with paper liners.
In a medium bowl, mix the graham cracker crumbs, sugar, melted butter, and salt until the mixture resembles damp sand. Divide the crust mixture evenly between the muffin cups, using about 1 1/2 tablespoons per liner. Press firmly into the bottoms.
Bake the crusts for 5 minutes, then remove from the oven and let them cool slightly while you prepare the filling.
In a large mixing bowl, beat the softened cream cheese until completely smooth. Add the Greek yogurt and sugar, then beat again until creamy.
Mix in the eggs one at a time on low speed. Add the vanilla extract, lemon juice, and lemon zest, then scrape down the bowl and mix just until combined.
If desired, toss the blueberries with cornstarch. Gently fold the blueberries into the cheesecake batter with a rubber spatula.
Divide the filling evenly among the muffin cups, filling each nearly to the top.
Bake for 18 to 22 minutes, or until the edges are set and the centers still have a slight jiggle. Turn off the oven and let the cheesecakes sit in the oven for 5 minutes with the door slightly cracked if desired.
Remove from the oven and cool at room temperature for 30 minutes. Transfer to the refrigerator and chill for at least 2 hours before serving.
Top with extra blueberries, lemon zest, whipped cream, lemon curd, or crushed graham crackers if desired. Serve chilled.