Preheat the oven to 325°F (163°C). Line two baking sheets with parchment paper.
In a medium bowl, whisk together the all-purpose flour, baking soda, and salt. Set aside.
In a large bowl, combine the melted butter, light brown sugar, and granulated sugar. Mix until smooth and creamy.
Add the vanilla extract, egg, and egg yolk to the butter and sugar mixture. Beat until well blended.
Gradually add the flour mixture to the wet ingredients, mixing until just combined. Do not overmix.
Fold in the semisweet chocolate chips evenly throughout the dough.
Using a tablespoon or cookie scoop, drop dough balls onto the prepared baking sheets about 2 inches apart.
Bake in the preheated oven for 11 to 13 minutes, or until the edges are set but the centers still look soft.
Remove the cookies from the oven and let them cool on the baking sheets for 5 minutes before transferring to a wire rack to cool completely.