01 - Preheat oven to 350°F. Grease a 9x13-inch baking dish 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 cream cheese, granulated sugar, egg, and vanilla extract with an electric mixer until completely smooth and creamy, about 2 minutes.
04 - Drop spoonfuls of the cheesecake mixture over the blueberry layer. Gently spread to create an even layer, being careful not to fully mix the two layers together.
05 - Sprinkle the lemon cake mix evenly over the entire surface, covering the cheesecake layer completely.
06 - Drizzle the melted butter evenly across the top of the cake mix, ensuring most of the dry mix is moistened. Use a spatula to gently spread the butter if needed.
07 - Bake for 40-45 minutes until the top is lightly golden brown and the edges are bubbling. The center should be set but still slightly moist.
08 - Let the cake cool for at least 15 minutes before serving to allow the layers to set. Serve warm or at room temperature, optionally topped with whipped cream or vanilla ice cream.