In a large bowl, mix together granulated sugar, all-purpose flour, cornstarch, baking soda, baking powder, and salt. Set aside.
In a skillet, melt 1 stick of butter on medium heat. Once melted, stir constantly with a rubber spatula until golden brown. Then, immediately pour into a mixing bowl. Add the remaining 1/2 stick of butter. Stir until the butter melts. Whisk in brown sugar until smooth. Then, add an egg, egg yolk, and vanilla extract. Whisk to combine.
Sprinkle the dry ingredients over this mixture. Stir using a rubber spatula until combined and no flour lumps remain. Cover with plastic wrap and transfer to the refrigerator for 1 hour.
Preheat the oven to 350ºF. Line two baking sheets with parchment paper. Remove the cookie dough from the refrigerator. Scoop about 2 tbsp of the dough and roll into a ball. Then, roll into granulated sugar. Place the cookie balls on the prepared baking sheets leaving at least 2 inches apart.
Bake for 11-13 minutes. Remove from the oven and let the cookies cool slightly on the baking sheet. Then, transfer to the cooling rack.