In a large mixing bowl, combine the softened butter, granulated sugar, and packed brown sugar.

Using an electric mixer, beat the mixture on medium speed for 2-3 minutes, until it becomes light, fluffy, and creamy.

Mix in the vanilla extract until fully incorporated.

Add the eggs one at a time, beating well after each addition. Scrape down the sides of the bowl as needed to ensure even mixing.

In a separate bowl, whisk together the flour, baking soda, and salt. This ensures even distribution of the leavening agent and salt.

With the mixer on low speed, slowly add the dry ingredients to the wet ingredients. Mix just until the flour streaks disappear. Overmixing can lead to tough cookies.

Using a rubber spatula or wooden spoon, gently fold in the chocolate chips or chunks until evenly distributed throughout the dough.

Cover the dough tightly with plastic wrap and refrigerate for at least 30 minutes (or up to 2 hours). Chilling the dough solidifies the fat, preventing the cookies from spreading too much during baking.

Preheat your oven to 375°F (190°C). Line baking sheets with parchment paper or silicone baking mats to prevent sticking.

Use a cookie scoop or tablespoon to drop rounded spoonfuls of dough onto the prepared baking sheets. Leave about 2 inches between each cookie to allow for spreading.

Bake for 9-12 minutes, or until the edges are golden brown and the centers are set. The cookies will continue to cook slightly on the baking sheet after being removed from the oven.

Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.