In a medium bowl, whisk together the all-purpose flour (300g or 2 ½ cups), baking soda (1 tsp or 5g), and salt (½ tsp or 3g). Whisking these dry ingredients together ensures they are evenly distributed, which is crucial for proper leavening and flavor.

In a large bowl, using an electric mixer (or a whisk and some elbow grease), cream together the softened unsalted butter (225g or 1 cup), granulated sugar (150g or ¾ cup), and packed brown sugar (150g or ¾ cup). Beat on medium speed until the mixture is light, fluffy, and pale in color, about 2-3 minutes. This process, called creaming, incorporates air into the dough, which contributes to the cookie's texture.

Add the large eggs (2) one at a time to the creamed butter and sugar mixture, beating well after each addition. Scrape down the sides of the bowl as needed to ensure everything is incorporated. This step helps to emulsify the wet ingredients.

Stir in the vanilla extract (2 tsp or 10ml) until just combined. Ensure the vanilla is evenly distributed throughout the wet ingredients.

Gradually add the dry ingredients (from step 1) to the wet ingredients (from step 4). Mix on low speed or stir with a wooden spoon until just combined. Be careful not to overmix; overmixing can develop the gluten in the flour, resulting in tough cookies.

Gently fold in the semi-sweet chocolate chips (340g or 2 cups) using a spatula or wooden spoon. Distribute them evenly throughout the dough. Ensure all the chips are coated in dough to prevent them from burning.

Cover the bowl with plastic wrap and refrigerate the dough for at least 30 minutes, or up to 24 hours. Chilling the dough is essential for several reasons: it allows the flavors to meld, prevents the cookies from spreading too much during baking, and results in a chewier texture. For crispier cookies, you can skip or shorten this step.

Preheat your oven to 190°C (375°F). Line baking sheets with parchment paper or silicone baking mats. This prevents the cookies from sticking and ensures even baking.

Scoop rounded tablespoons (about 2 tbsp or 30g) of chilled dough onto the prepared baking sheets, leaving about 5cm (2 inches) of space between each cookie. This allows them to spread without touching each other. Using a cookie scoop ensures uniform size, which leads to even baking.

Bake for 9-12 minutes, or until the edges are golden brown and the centers are still slightly soft. The exact baking time will depend on your oven and the size of your cookies. For softer, chewier cookies, err on the side of underbaking slightly. For crispier cookies, bake for a minute or two longer.

Let the cookies cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely. This resting period on the hot baking sheet allows the cookies to set up properly, preventing them from breaking when moved.

Once completely cooled, store the cookies in an airtight container at room temperature for up to 3-4 days. If you want to keep them soft, place a slice of bread in the container.