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 vanilla extract and egg yolk, mixing until well combined.
In a separate bowl, whisk together the flour, baking soda, and salt.
Gradually blend the dry ingredients into the wet mixture until just combined.
Fold in the chocolate chips.
Scoop tablespoon-sized balls of dough onto a parchment-lined baking sheet.
Flatten each ball slightly with the back of a spoon.
Bake in the preheated oven for 8-10 minutes, or until 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.