Position a rack in the center of the oven. Pre-heat oven to 350oF (180℃). Prepare a baking sheet with parchment paper (or silicone baking mat).
Start by measuring your flour (I recommend using a kitchen scale). But if measuring by volume, then first stir the flour in the bag/container as flour tends to settle. Then spoon the flour into your measuring cup, and then level it off at the top. Do not pack it down into the cup, or tap the sides as more flour will pack into the cup. Add the flour to your mixing bowl. Whisk together flour, baking soda, baking powder and salt into a bowl. Set aside. 3 cups (360 g) all purpose flour 1 teaspoon baking soda ½ teaspoon baking powder 1 teaspoon salt
Using a mixer fitted with paddle attachment, cream butter and sugar together until very light, about 2-3 minutes. 1 cup (2 sticks, 227 g) unsalted butter 2 cups (414 g) packed light brown sugar
Add eggs, one at a time, mixing well after each addition. Stir in the vanilla. 2 large eggs 2 teaspoons pure vanilla extract
Reduce speed to low, add dry ingredients and mix until just combined, 5 to 10 seconds. This will be a thick dough but it's supposed to be, don't worry! Add chocolate and stir in, on low speed, just until combined. You can chill the cookie dough at this point (at least 2 hours, ideally overnight) for cookies that spread less and bake up thicker and chewier. 12 ounces semi-sweet chocolate chips
Scoop cookie dough, using a medium cookie scoop (size #40) that holds 2 tablespoons, and place on prepared cookie sheet. Bake until golden brown but still soft, 10-12 minutes. The top of the cookies should be puffy but set, and edges golden brown. Transfer sheet to a wire rack for 10 minutes, then slip cookies onto another rack to cool a bit more. Repeat with remaining dough, or reserve dough, refrigerated, for baking remaining batches the next day.