Preheat oven to 350°F (175°C). Line an 8x8-inch pan with parchment paper.
Mix graham cracker crumbs, melted butter, and sugar in a bowl.
Press crust mixture into prepared pan. Bake for 8 minutes and cool slightly.
Beat cream cheese until smooth. Add sugar, vanilla, and egg. Mix until creamy.
Spread cream cheese filling over crust.
In a saucepan, combine blueberries, sugar, cornstarch, and lemon juice. Cook 4–5 minutes until slightly thickened.
Spoon blueberry mixture over cream cheese filling.
Bake 30–35 minutes until center is mostly set.
Cool completely, then refrigerate at least 2 hours before slicing.
Garnish with powdered sugar or lemon zest if desired.