Spray a jelly roll pan with non-stick spray or grease the pan.
In a medium mixing bowl, blend cake mix, butter, and eggs together.
Lightly pat the mixture evenly over the bottom of the jelly roll pan.
Place cream cheese, sugar, and, vanilla in a 2-quart bowl. Beat with a mixer on medium speed until smooth.
Pour and spread the mixture over the cake mix layer.
Place the pan on the center rack of the oven and bake at 350 degrees for 30 to 35 minutes or until golden brown and the top looks like a nicely baked cheesecake.
Cool the cake in the pan on a wire rack for 1 hour.
Cut the cake into neat squares but do not remove them from the pan.
Cover the cake with plastic wrap and refrigerate it for a few days before serving.