Preheat the oven to 325°F and line 2 baking sheets with parchment paper or silicone baking mats.
Whisk the flour, baking soda, cornstarch and salt together. Set flour mixture aside.
1 3/4 cups all purpose flour, 1 tsp. baking soda, 1 tsp. cornstarch, 1 tsp. kosher salt or 1/2 tsp. fine salt
Combine the brown sugar and white sugar together, breaking up any lumps of brown sugar with your fingertips.
3/4 cup dark brown sugar, packed (light brown will be OK too), 1/4 cup granulated white sugar
Whisk the cooled melted butter into the sugars for ~ 1-2 minutes, it should look like a paste.
1/2 cup unsalted butter, melted and cooled for ~10 minutes
Add in one egg, whisk until smooth. Then add the egg yolk and vanilla and whisk again until smooth, ~ 1 minute.
1 large egg, room temperature, 1 large egg yolk, room temperature, 1 Tbsp. pure vanilla extract
Fold in dry ingredients just until incorporated, do not over mix.
Scoop using a 2 Tbsp. scoop (these cookies spread a bit so dont overcrowd the cookie sheet, I bake 6 cookies per cookie sheet) you should get ~14-16 cookies. To get the cookies to look like the photos, scoop and place right on the cookie sheet, don’t roll in a ball between the palms of your hands and keep them 2 tbsp in size .❤️
Bake for ~11-13 minutes. The cookies will look puffed and slightly underbaked in the middle and the edges will be golden brown. They cook more on the sheet once removed from the oven. While the cookies are still warm, I like to place a circular cookie cutter or a circular drinking glass around the cookies (it should be larger than the cookie so you don’t cut off any edges) and give the cookies a spin to give them a perfect circular shape.
Cool on the cookie sheet 10-15 minutes, remove to cooling rack to cool completely. They will flatten as they cool and get perfectly soft as they cool. Add flaky sea salt on top and ENJOY!
flaky sea salt (such as Maldon) for finishing