Brown the butter: Place butter in a light-colored saucepan over medium heat. Stir frequently as it melts and begins to foam. Once you see golden brown bits forming at the bottom and it smells nutty and caramel-like, immediately remove from heat.

Cool the butter: Pour the browned butter into a large mixing bowl and let it cool for 10–15 minutes. You want it warm but not hot.

Combine sugars: Add the dark brown sugar and granulated sugar to the cooled brown butter. Stir well until fully combined and smooth.

Add eggs and vanilla: Crack in both eggs and add the vanilla extract. Mix until the batter looks glossy and slightly thickened, about 1 minute.

Add the dry ingredients: Add the flour, cornstarch, baking powder, baking soda, and salt. Stir until just combined — stop as soon as you no longer see dry flour.

Fold in the chocolate chips: Gently fold in the chocolate chips (and chunks if using) until evenly distributed throughout the dough.

Scoop and bake: Preheat your oven to 350°F. Scoop dough onto a parchment-lined baking sheet, spacing cookies about 2 inches apart. Bake for 10–12 minutes until the edges are set and golden but the centers still look slightly underdone.

Cool and enjoy: Let cookies rest on the baking sheet for 5 minutes before transferring to a wire rack. They firm up as they cool — if they last that long!