Preheat oven to 350°F (175°C). Crush graham crackers until fine crumbs. Melt butter and combine with crumbs, press into the bottom of a square baking dish. Bake for 10 minutes until golden, then cool completely.

In a large bowl, beat cream cheese and powdered sugar together until smooth. Add lemon juice and blend for another minute. Pour over cooled crust, spreading evenly.

Rinse blueberries, pat dry. Distribute evenly over the cream cheese layer.

Cover with plastic wrap and refrigerate for at least 4 hours. Overnight is best for setting.

Slice into squares and serve chilled, garnishing with extra blueberries or mint if desired.