Preheat oven to 350 degrees. Line a cookie sheet with parchment.

Mix butter and sugars until smooth.  Add egg yolk and vanilla.  Sprinkle flour, baking soda, and salt on top and then mix together.  Add chocolate chips and/or any other mix-ins.

Form dough into one large ball and place on prepared baking sheet.  Gently press down to about 1/2 – 3/4 inch thick.  Bake until edges are set and center looks cooked, but still soft.  You’ll want to keep an eye on it since baking time can vary depending on how much you press your dough down.  Mine usually take about 15 minutes.

Let cool for 10 minutes before digging in (or don’t.  You’re the boss here.)  Enjoy!