Spread the lemon pie filling into the bottom of a 9×13-inch baking dish.
In a medium mixing bowl, beat the cream cheese, egg, and granulated sugar with an electric mixer until smooth. Drop spoonfuls of the cream cheese mixture over the lemon pie filling.
Sprinkle the dry cake mix evenly over the pie filling and cream cheese layer.
Slice thin pats of butter and place evenly over the top of the dry cake mix.
Bake the dump cake for 40 minutes or until the top is turning golden brown.
Remove the cake from the oven and allow to rest for 15 minutes at room temperature before serving.
