12Tablespoons (1 1/2 sticks)unsalted butter,softened and divided
2cupsall purpose flour
2Tablespoonscornstarch
1teaspoonbaking powder
1/2teaspoonkosher salt(plus extra for sprinkling, if desired)
1largeegg
1large egg yolk
2teaspoonsvanilla extract
1cupbrown sugar
1/2cup granulated sugar
1 - 1 1/2cupschocolate chips(see note)
Instructions
Heat 6 Tablespoons of the butter in a small skillet over medium high heat. Cook until it becomes golden brown and fragrant, then pour into a heat proof bowl or measuring cup. Cool completely.
Whisk together the flour, cornstarch, baking powder, and salt in a medium bowl.
In a small bow, lightly beat together the egg and egg yolk, then stir in the vanilla.
Add the remaining 6 Tablespoons of softened butter and the cooled browned butter to the bowl of a stand mixer. Cream on medium high speed until fluffy. Add the brown sugar and granulated sugar and continue to cream together on medium high speed until it resembles wet sand. Add the egg mixture and continue to beat until it's light and fluffy.
With the mixer turned off, add the flour mixture. Turn to low speed and mix just until the flour is incorporated (about 1 minute). Add the chocolate chips and mix just until incorporated.
Transfer dough to an airtight container or wrap tightly in plastic. Chill for at least 2 hours or overnight.
Heat oven to 350°F. Prepare 2 baking sheets by lining them with parchment or silicone baking mats (NOTE: Cookies baked on silicone mats will spread more than those baked on parchment). Scoop dough (it will be firm) in about 1 1/2 to 2 Tablespoon portions. Form into slightly flattened balls and place 2 inches apart on prepared baking sheets. Sprinkle the tops of the dough VERY lightly with additional kosher salt if desired.
Cook until the edges are just beginning to brown, aobut 15-20 minutes. Cool for 10 minutes on the baking sheet, then transfer to a cooling rack to cool completely. Store in an airtight container or freezer bag at room temperature or in the freezer.
Notes
Use 1 cup chocolate chips if you like your cookies with a normal amount of chocolate, but use up to 1 1/2 cups if you like them extra chocolatey.