Preheat oven to 350°F (177°C) and line two baking sheets with parchment paper. A common mistake is putting dough on a hot tray from a previous batch, so let baking sheets cool completely between rounds to avoid extra spreading.
In a medium bowl, whisk the flour, baking soda, and salt until evenly combined. The visual cue is a uniform flour mixture with no streaks of baking soda, which helps cookies bake evenly.
In a large bowl, beat butter, granulated sugar, and brown sugar for about 2 minutes until light and fluffy. You are looking for a creamy, slightly lighter mixture, not oily or separated, so stop once it looks smooth.
Beat in the eggs one at a time, then mix in vanilla until combined. The mixture should look glossy and smooth, and the biggest mistake here is overbeating, which can make cookies puff too much and then collapse.
Add dry ingredients to the wet ingredients and mix just until no flour remains. The dough should be soft and thick, and it should hold its shape when scooped, not pour or smear.
Fold in chocolate chips until evenly distributed. Mix gently so the dough stays tender and the chocolate does not get crushed into the batter.
Scoop dough into 2-tablespoon mounds and place on the baking sheet about 2 inches apart. For even-sized cookies, a scoop helps, and it prevents accidentally making some cookies overbake while others stay underdone.
Bake for 11 minutes until edges are set and golden, but centers still look slightly soft. Cool on the baking sheet for 10 minutes, then transfer to a rack so the cookies finish setting while staying soft in the middle.