Preheat your 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. Stir until smooth and creamy.
Add the egg and egg yolk to the butter and sugar mixture and whisk until fully incorporated.
Stir in the vanilla extract.
Gradually add the dry ingredients to the wet ingredients, mixing just until combined. Do not overmix.
Fold in the semisweet chocolate chips evenly throughout the dough.
Using a large cookie scoop or 1/4 cup measuring cup, drop dough balls onto the prepared baking sheets, spacing them about 3 inches apart.
Bake for 12 to 15 minutes, or until the edges are set and lightly golden but the centers still look soft.
Remove from the oven and allow the cookies to cool on the baking sheet for 10 minutes before transferring to a wire rack to cool completely.