01 - Preheat oven to 350°F. Grease a 9x13-inch baking dish thoroughly with cooking spray or butter.
02 - Spread fresh or frozen blueberries and blueberry pie filling evenly across the bottom of the prepared dish. Sprinkle lemon zest over the surface and drizzle with lemon juice.
03 - In a medium bowl, beat softened cream cheese, granulated sugar, egg, and vanilla extract until completely smooth and creamy, about 2 minutes.
04 - Drop spoonfuls of the cheesecake mixture over the blueberry layer. Gently spread to cover most of the surface without fully mixing into the fruit layer.
05 - Sprinkle the lemon cake mix evenly over the entire surface, creating a uniform layer.
06 - Drizzle melted butter evenly over the cake mix, ensuring most of the dry mix is moistened. The surface will appear uneven and textured.
07 - Bake for 40–45 minutes until the top is lightly golden brown and the edges are bubbling. The center should be set but slightly moist.
08 - Let the cake cool for 15 minutes before serving. Serve warm or at room temperature, optionally topped with whipped cream or vanilla ice cream.