Get the oven preheating to 350 degrees F. Line a baking sheet with parchment paper.
In a medium bowl, stir together the softened butter and sugars until combined.
Mix in the egg yolk and vanilla until well combined.
Stir in flour, baking soda, and salt. Then fold in the chocolate chips and oats.
Chill the dough in the fridge for 10-15 minutes while the oven finishes preheating.
Roll the dough into two balls and place on a baking sheet.
Press a few extra chocolate chips in the tops for extra pretty cookies.
Bake for 11–13 minutes until the edges are golden and set and the centers are just set.
Allow the cookies to cool on the baking sheet for about 10 minutes.
