Preheat the oven to 350°F (175°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 unsalted butter, brown sugar, and granulated sugar. Mix until smooth and creamy.
Add the large egg, egg yolk, and vanilla extract to the butter and sugar mixture. Beat until well combined.
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 rounded dough balls onto the prepared baking sheets, spacing them about 2 inches apart.
Bake in the preheated oven for 10 to 12 minutes, or until the edges are set but the centers remain soft and slightly underbaked.
Remove the cookies from the oven and allow them to cool on the baking sheets for 5 minutes before transferring to a wire rack to cool completely.