Preheat oven to 350 degrees and line a square baking dish with parchment paper. Leave enough over the sides so you can lift the bars out easily once done.
Add your graham crackers to a food processor and blend until they are fine crumbs.
Add the graham cracker crumbs to a medium bowl and add in the melted butter & sugar. Mix until fully combined.
Pour graham cracker mixture into pan and press down until firm. Bake for 10 minutes.
While your crust is baking, make the filling. Use a handheld or standing mixer and beat the cream cheese by itself until smooth. Then, add in the egg, lemon juice & zest, sugar and vanilla. Beat until creamy.
Fold in the blueberries with a spoon or spatula.
Layer the filling and spread evenly on top of graham cracker crust. Bake for 35 minutes or until the edges have started to golden.
Let cool for about 30 minutes at room temperature before chilling in the fridge for 3-4 hours.
When ready to serve, cut into squares!