01 - Preheat the oven to 175°C. Lightly grease a 23x33 cm baking dish.
02 - Spread the lemon pie filling evenly in the prepared baking dish.
03 - In a medium mixing bowl, beat together softened cream cheese, sugar, egg, and vanilla extract until smooth and creamy.
04 - Drop spoonfuls of the cream cheese mixture evenly over the lemon filling, then gently swirl with a spatula or knife.
05 - Sprinkle the dry yellow cake mix evenly over the entire surface.
06 - Drizzle the melted butter evenly over the cake mix, covering as much area as possible.
07 - If desired, sprinkle lemon zest over the top for extra flavor.
08 - Bake in the preheated oven for 40–45 minutes, until the top is golden and the edges are bubbling.
09 - Allow to cool for at least 15 minutes before serving warm or at room temperature.