Preheat your oven to 350 degrees F.
Spray a 13x9-inch baking pan with nonstick spray.
In a large bowl, combine the cake mix, 1 egg, and 1 stick of melted butter. Use an electric mixer to blend until well combined.
Pat the mixture evenly into the bottom of the prepared pan.
In a separate large bowl, beat the cream cheese until smooth and creamy.
Add the remaining 2 eggs, vanilla, and the other stick of melted butter. Mix until well combined.
Gradually add the powdered sugar to the cream cheese mixture, mixing well until smooth.
Spoon the creamy mixture over the cake batter and spread evenly.
Sprinkle the fresh blueberries on top.
Bake for 40 to 50 minutes, until set but gooey in the center.
