Begin by creaming together unsalted butter and full-fat cream cheese in a large mixing bowl using a hand mixer. Beat until smooth and creamy, about 2 minutes.

Gradually add in brown sugar and granulated sugar, mixing until fluffy. Then, incorporate the egg and vanilla extract, blending until well combined.

In a separate bowl, whisk together all-purpose flour, cornstarch, baking soda, and salt. This combination of dry ingredients will give the perfect texture.

Carefully add the dry ingredients to the wet mixture. Mix on low speed, just until no dry flour remains visible.

Gently fold in chocolate chips using a spatula, ensuring they are evenly distributed.

Cover your dough with plastic wrap and refrigerate for at least 2 hours, or overnight if you can wait.

Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper. Scoop tablespoon-sized portions of the chilled dough onto the sheets.

Bake for 9-11 minutes, until the edges are set and the centers look slightly soft.

Once done, let them cool on the baking sheet for 5 minutes before transferring to a wire rack.