1-Step 1: Prepare Your Equipment and Oven Preheat your oven to 400°F. This high temperature is crucial for creating thick cookies with crisp exteriors and soft interiors. Line a baking sheet with parchment paper to prevent sticking and make cleanup easy. Parchment paper also helps the cookies bake evenly.

2-Step 2: Cream Butter and Sugars In a stand mixer fitted with the paddle attachment, combine your cold, cubed butter with all three sugars. Mix on low speed for 30 seconds to incorporate, then increase to medium speed and beat for 4 full minutes. This extended mixing time is essential because it creates air pockets in the cold butter, which helps the cookies puff up and stay thick. The mixture should be light and fluffy when finished.

3-Step 3: Add Wet Ingredients Add the eggs, vanilla, kosher salt, baking soda, and cornstarch to the butter-sugar mixture. Mix on medium speed for 1 minute until completely smooth. Stop to scrape down the sides of the bowl as needed to ensure everything incorporates evenly. The cornstarch at this stage helps create that signature soft interior texture.

4-Step 4: Incorporate the Flour With the mixer on low speed, gradually add the all-purpose flour. Mix only until just combined. Overmixing at this stage develops gluten and can result in tough, cakey cookies rather than soft, chewy ones. You want to see just a few streaks of flour remaining when you stop the mixer.

5-Step 5: Fold in Chocolate Chips and Walnuts Keep the mixer on low speed and add the chocolate chips and chopped walnuts. Mix until they’re evenly distributed throughout the dough. You can also do this step by hand using a wooden spoon or spatula if you prefer more control over the mixing.

6-Step 6: Portion the Dough Using a 3-tablespoon cookie scoop, portion the dough into generous balls. Place them on the prepared baking sheet, spacing them 2 inches apart to allow for spreading. A larger scoop creates those bakery-style thick cookies that everyone loves. If you don’t have a cookie scoop, use a measuring cup or roll the dough by hand.

7-Step 7: Bake to Perfection Bake the cookies for 8-9 minutes until the edges and tops are lightly golden. The centers may still look slightly underdone, but they’ll continue cooking on the hot baking sheet. This is the secret to soft, chewy centers! Avoid overbaking, as the cookies will become crisp throughout rather than maintaining that perfect texture contrast.

8-Step 8: Cool and Serve Let the cookies cool on the baking sheet for 2-3 minutes after removing them from the oven. This resting period allows them to set properly. Then transfer them to a wire rack to cool completely. The cookies will firm up as they cool, developing that ideal texture.