Gather all your ingredients and measure them out.
In a large mixing bowl, combine softened cream cheese, powdered sugar, and sour cream. Mix until smooth and creamy.
In another bowl, combine lemon cake mix, melted butter, water, and vanilla extract. Whisk until just combined.
Spread the cream cheese mixture evenly in a greased baking dish. Pour the lemon cake batter over it and sprinkle blueberries on top if using.
Preheat the oven to 350°F. Bake for 40-45 minutes until golden brown and a toothpick comes out clean.
Allow the cake to cool for 15 minutes before serving.