Preheat the oven to 350 degrees Fahrenheit. Line a muffin tin with 9 liners and fill up half of the other empty cups with water. This ensures even baking.
In a food processor, pulse the 4 sheets graham crackers to crumbs. Stir in 1 tablespoon granulated sugar and 2 tablespoons butter,. Press an even amount of graham cracker crust into the bottom of each muffin liner, about 1 tablespoon.
Press down the crust with the backside of a measuring spoon and set aside.
Filling
In a medium-sized bowl, combine the softened 1 (8-ounce) package cream cheese, and ½ cup granulated sugar. Beat until smooth and creamy. Add ½ teaspoon vanilla extract, 1 large egg, and ½ teaspoon lemon zest Beat until combined.
Spoon the cheesecake filling evenly between the 9 cups and bake for 20-22 minutes. The centers will still jiggle a little bit, but the edges should be a very light brown.
Remove from the oven and let cool at room temperature for 30 minutes and then transfer to the fridge and let cool for at least 2 hours. The cheesecakes may have risen in the oven and will deflate quite a bit while cooling.
Topping
Once the cheesecakes have been cooled, place 4 tablespoons of blueberry jam in a small bowl and microwave for 20-25 seconds. Spoon ½ tablespoon of jam on top of each cheesecake and spread to cover the top.
Immediately top with ½ pint blueberries.
Add the remaining 2 tablespoons in the same small bowl and microwave for 10-15 seconds. Using a pastry brush, brush the tops of all of the fresh blueberries with the jam. Sprinkle powdered sugar on top if desired.