I begin by creaming the softened butter with the sugar, beating until smooth and creamy. Then I stir in the egg and vanilla until blended. Next I add the baking soda, salt, and flour; I gently mix just until a soft cookie dough forms. After that, I fold in ¼ cup of the chocolate chips so they’re spread through the dough.
I pop the dough into the freezer (or fridge) for 20 minutes — this step is essential. Chilling firms the fat and prevents excessive spreading in the oven. Without chilling, the cookies may turn thin and flat.
I scoop dough balls and place them on prepared baking sheets about 3 inches apart. Then I bake them at 350 °F (175 °C) for ~10 minutes, but remove them while still slightly underbaked, puffy, and light in color — they settle as they cool. While still hot, I press the remaining 2 tablespoons of chocolate chips into the tops for a prettier look. Let the cookies cool for 15 minutes on the baking sheet before transferring to a rack.