Preheat and prep: Heat your oven to 350°F (175°C).
Lightly grease a 9x13-inch baking dish with nonstick spray or butter.
Lay down the lemon: Spread the lemon pie filling evenly across the bottom of the dish. Sprinkle on the lemon zest if using for extra brightness.
Whip the cream cheese layer: In a bowl, beat the softened cream cheese with the sugar, vanilla, and a pinch of salt until smooth. Dollop this mixture over the lemon layer in spoonfuls.
It doesn’t have to be perfect—little pockets are great.
Add the cake mix: Evenly sprinkle the dry cake mix over everything. No stirring. Aim for a level blanket of mix without thick mounds.
Finish with butter: Drizzle the melted butter slowly and evenly across the surface.
Try to cover as much dry mix as possible. If you like, add a few small pats of butter over any dry spots.
Bake: Place in the oven and bake for 35–45 minutes. You’re looking for a golden, crisp top and bubbling edges.
The center should be set but still a little soft underneath.
Cool slightly: Let the cake sit for 10–15 minutes. It will firm up a bit as it cools, making scooping easier.
Serve: Spoon into bowls and serve warm, at room temperature, or chilled. Top with whipped cream or a dusting of powdered sugar, and add berries if you want a fresh pop.