Preheat oven to 350°F (175°C) and grease a 9x13 inch baking dish.

Spread the lemon pie filling evenly across the bottom of the prepared dish.

In a small bowl, beat the cream cheese and sugar until smooth, then dollop small spoonfuls over the lemon filling.

Sprinkle the dry lemon cake mix evenly over the top of the filling and cream cheese layers.

Place the thin slices of butter across the entire surface of the cake mix, ensuring as much coverage as possible.

Bake for 40 to 45 minutes or until the top is golden brown and the edges are bubbly.

Allow to cool for at least 15 minutes before serving to let the layers set.