Preheat your oven to 325 degrees Fahrenheit. Line 2 baking sheets with parchment paper and set aside.
In a large mixing bowl, beat together the softened butter, brown sugar, and granulated sugar until light and fluffy.
Add the egg, egg yolk, and vanilla extract. Mix until just combined.
In a separate bowl, whisk together the flour, quick oats, baking soda, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until combined. Fold in the chocolate chips.
Using a 1/4 cup measuring cup or cookie scoop, portion the dough into balls and place them on the prepared baking sheets, leaving 1–2 inches between each cookie.
Bake for 12–15 minutes, or until the edges are lightly golden brown and crisp.
Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire cooling rack.