Preheat your oven to 175°C and lightly grease a 23 × 33 cm baking dish.
Spread the strawberry pie filling evenly across the bottom of the prepared dish, making sure it reaches all corners.
In a bowl, combine the cream cheese, granulated sugar, vanilla extract, milk, and sour cream. Mix until smooth and creamy, with no visible lumps.
Spoon the cream cheese mixture over the strawberry layer in small dollops, leaving gaps so it stays marbled rather than fully blended.
Sprinkle the dry cake mix evenly over the entire surface. Do not mix or press it down.
Slowly drizzle the melted butter over the cake mix, covering as much of the surface as possible to help it bake evenly.
Bake for 45–55 minutes, until the top is golden brown and the strawberry filling is bubbling up around the edges.
Remove from the oven and let it rest for at least 15 minutes before serving to allow the layers to set.