Preheat your oven to 350°F (175°C). This is a crucial step as it ensures that your cookies bake evenly.
Line a baking sheet with parchment paper. This will prevent the cookies from sticking and make for easy cleanup.
In a medium bowl, whisk together the all-purpose flour, baking soda, and salt. Set this mixture aside while you prepare the wet ingredients.
In a large mixing bowl, combine the melted butter, brown sugar, and white sugar. Use a whisk to blend them until smooth. Add in the vanilla extract, egg, and egg yolk. Beat until the mixture is light and creamy.
Gradually add the dry ingredient mixture to the wet ingredients. Stir with a rubber spatula until just combined. Be careful not to overmix; a few flour streaks are okay.
Gently fold in the semisweet chocolate chips until evenly distributed throughout the dough.
Using a cookie scoop or tablespoon, drop generous portions of dough onto the prepared baking sheet, spacing them about 2 inches apart.
Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden. The centers may look underbaked, but they will continue to set as they cool.
Allow the cookies to cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely. Enjoy them warm with a glass of milk or your favorite beverage!