In a large mixing bowl, combine the melted butter, granulated sugar, and light brown sugar. Whisk until well combined and smooth.

Beat in the egg, egg yolk, and vanilla extract until the mixture is light in color and fluffy, about 1-2 minutes with an electric mixer.

In a separate medium bowl, whisk together the all-purpose flour, baking soda, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing on low speed (or by hand with a spatula) until just combined. Be careful not to overmix.

Gently fold in the chocolate chips until evenly distributed throughout the dough.

Cover the bowl with plastic wrap and refrigerate the dough for at least 30-60 minutes. Chilling helps prevent spreading and deepens flavor. For best results, chill for 2-24 hours.

Preheat your oven to 375°F (190°C). Line two large baking sheets with parchment paper.

Scoop rounded tablespoons or 1.5-ounce portions of dough onto the prepared baking sheets, leaving about 2 inches between each cookie.

Bake one sheet at a time for 10-12 minutes, or until the edges are golden brown and the centers are still slightly soft. They will continue to set as they cool.

Remove from the oven and let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire cooling rack to cool completely.