In a large bowl, toss together the flour, baking soda, cornstarch and salt. Set aside.
2 and ¼ cups (270g) all-purpose flour, 1 teaspoon baking soda, 2 teaspoons cornstarch, 1 teaspoon salt
In a medium sized bowl, whisk together the melted butter, brown sugar, and granulated sugar. When sugar clumps disappear, whisk in the egg, egg yolk, and vanilla.
1 cup (227g) unsalted butter, 1 cup (200g) firmly packed light brown sugar, ½ cup (100g) granulated sugar, 1 large egg + 1 large egg yolk, 1 and ½ teaspoons vanilla extract
Pour the wet ingredients into the dry ingredients and mix together with a large spatula. Fold in the chocolate chips and stir until evenly dispersed.
1 and ½ cups (255g) chocolate chips3
Chill the dough: roll the chilled dough into balls4 (I use this #50 cookie scoop for all of my standard size cookies) and place balls of dough onto a large baking sheet, large platter, or something else flat that you can stick in the refrigerator so the dough can chill. You could also chill the whole bowl of dough, but this dough is difficult to scoop once chilled, and chilling is mandatory. Cover the dough balls/bowl of dough and chill in the refrigerator for at least 2 hours and up to 3 days.
When you are ready to bake the cookies, move a rack to the middle position in the oven, then preheat it to 350ºF (177ºC). Line two large baking sheets with parchment paper or silicone baking mats and set aside.
Place no more than 8 balls (with a preference of 6) of dough onto each cookie sheet. If you like, you can press a few more chocolate chips on top/sides of the dough balls for aesthetic purposes. Keep dough/dough balls that are waiting to bake chilled.
Bake the cookies for 10-11 minutes or until edges just start to turn brown. Remove from oven and allow cookies to cool on the baking sheet for 5-10 minutes before moving to a wire rack to cool completely. You can reshape cookies while they are hot using a round cookie cutter or the rim of a mug or glass if they're more misshapen than you prefer. Store cookies in an airtight container at room temperature, up to 7 days. Baked cookies may be frozen up to 3 months. You may also freeze rolled cookie dough up to 3 months. Bake frozen for 11-12 minutes.
Video
Notes
Melted butter: take care to melt the butter just until it's melted and not foamy. My best tip is to melt it until there is still some stick visible, then stir it to help distribute the heat to melt the rest of the butter. If the butter becomes foamy, you may be losing too much moisture which could drastically affect the success of the cookie.
Room temperature eggs: these are preferred for even distribution into batter. As a rule of thumb, when a recipe calls for room temperature or melted butter, it's generally a good idea to use room temperature eggs as well. If you don't have time to let eggs come to room temperature, place them in a bowl of warm water for 5-10 minutes before using.
Chocolate chips:I prefer to use a combination of 1 cup milk or semi-sweet standard size chocolate chips and ½ cup mini semi-sweet chocolate chips for these cookies.
Balls of dough: I have made these by just dropping cookie dough right from the scoop onto the baking sheet and also rolling the balls smooth with my hands. Dropping will give your cookies extra texture on the outside while rolling will make the cookies a little more uniform in texture. I do not prefer one way or the other, and the taste is exactly the same.
Mini cookies: I do not recommend using this recipe to make mini cookies. Use my carefully tested recipe if you are looking for mini chocolate chip cookies.
If your cookies are spreading: in my decade of experience with folks making my chocolate chip cookies, you can do everything right (weighing flour, chilling dough) and your cookies can still spread. Try reducing your oven temperature to 325ºF (163ºC).
All nutritional values are approximate and provided to the reader as a courtesy. Changing ingredients and/or quantities will alter the estimated nutritional calculations.