Preheat your oven to 350°F (175°C).
In a mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until smooth.
Add the egg yolk and vanilla extract, mixing until well combined.
In a separate bowl, whisk together the flour, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Fold in the chocolate chips.
Scoop tablespoon-sized portions of dough onto a baking sheet lined with parchment paper.
Bake for 10-12 minutes, or until the edges are lightly golden.
Remove from the oven and let cool on the baking sheet for a few minutes before transferring to a wire rack.
Enjoy your freshly baked cookies with a glass of milk!