Combine cake mix, one stick of melted butter, and 1 egg, and press into the bottom of a greased 9x13 Pyrex.
Beat softened cream cheese, 1 stick of melted butter, 1 teaspoon vanilla, and powdered sugar until smooth, and then pour over crust. Add blueberries.
Bake at 350F for 40-50 mins. Center will be soft but will firm as it cools.