Preheat your oven to 375°F and line a baking sheet with parchment paper or a silicone baking mat.
In a medium bowl, whisk together the all-purpose flour, cornstarch, baking powder, baking soda, and salt.
In a stand mixer fitted with a paddle attachment, cream together the unsalted butter, brown sugar, and granulated sugar on medium speed for about 2-3 minutes.
Add the large egg and vanilla extract to the creamed mixture. Beat on medium speed for another minute until fully combined and smooth.
Gradually add the dry ingredient mixture to the wet ingredients, mixing until just combined.
Gently stir in the Guittard baking chips using a spatula or wooden spoon until evenly distributed throughout the dough.