1-First Step: Mixing the Dry Ingredients In a medium bowl, whisk together the all-purpose flour, baking soda, and a pinch of salt. Skipping this step or adding the leavening later can lead to uneven spots in your cookies, giving some a soapy taste while others remain flat. Whisking aerates the flour and incorporates the baking soda evenly.

2-Second Step: Creaming the Butter and Sugars In a large bowl, or the bowl of a stand mixer, beat the softened butter, white sugar, and brown sugar together on medium speed. You want to do this for about 2 to 3 minutes until the mixture is pale and fluffy. This process creates air pockets in the butter, which helps the cookies rise. Scrape down the sides of the bowl to ensure everything is well incorporated.

3-Third Step: Adding Eggs and Flavor Add the vanilla extract and the eggs one at a time, beating well after each addition. This step emulsifies the eggs into the fat, creating a stable structure for the cookie. If you add both eggs at once, the dough might curdle or separate, affecting the final texture.

4-Fourth Step: Combining Wet and Dry Reduce the mixer speed to low and gradually add the dry flour mixture. Mix only until the flour streaks disappear. Overmixing at this stage develops too much gluten, resulting in tough, hard cookies rather than soft, chewy ones. The dough should be thick and sticky.

5-Final Step: Baking to Golden Perfection Fold in the semi-sweet chocolate chunks by hand using a spatula. Scoop the dough onto the prepared baking sheets using a 1/4 cup measuring scoop to achieve that iconic Costco size. Space them about 2 inches apart. Bake for 12 to 15 minutes, or until the edges are golden brown but the centers still look slightly underbaked. They will continue to cook on the hot pan. Let them cool on the baking sheet for 5 minutes before transferring to a wire rack.