Add butter, cream cheese, egg, vanilla, and both sugars to a mixing bowl. Beat on speed 6 for 3-4 minutes if using a stand mixer. For hand mixers, beat on medium high for 5 minutes or until light and creamy.
Add flour, cornstarch, and baking soda. Mix on low for less than one minute until combined. Be sure to not overmix.
Fold in chocolate chips by hand. Scoop into equally sized balls of dough and refrigerate.
Preheat the oven to 350 degrees and bake for exactly 10 minutes, or until the edges are light brown and the center is still light. Let cool and enjoy!