Preheat the oven to 350 degrees F. Spray a 13x9-inch pan with nonstick spray.
In a large bowl, use an electric mixer to combine the cake mix, 1 egg, and 1 stick of melted butter until well combined. Pat the mixture into the bottom of the prepared pan.
In a separate large bowl, use an electric mixer to beat the cream cheese until smooth.
Add 2 eggs, vanilla, and the remaining 1 stick of butter (melted) and beat to combine.
Next, add the powdered sugar and mix well.
Spoon this mixture over the cake batter and use the spoon to spread to create an even layer.
Sprinkle the fresh blueberries on top. Bake for 40 to 50 minutes- just until the cake seems set but is a little gooey in the center.
