Preheat oven to 300 degrees and spray a 9 x 13 inch dish with cooking spray. Mix cake mix, butter, and one egg to form a soft dough. Press into the bottom of the pan. Mix powdered sugar, softened cream cheese and remaining two eggs until smooth, about 1-2 minutes. Pour on top of crust. Bake at 300 for 40-50 minutes, until the top is golden brown.