Combine dry ingredients (Flour, Baking Soda, Cream of Tartar and Salt) in large mixing bowl.
Whisk dry ingredients until combined.
Add butter + sugar in a separate large mixing bowl.
Whisk butter with sugar until well-combined (approx. 60 seconds).
Add other wet ingredients (Egg Yolks, Vanilla Extract) to combined Butter + Sugar and whisk for 30 seconds each until combined.
Add wet ingredients into bowl with dry ingredients and fold until just combined.
Preheat oven to 350*F and line cookie sheet with parchment paper.
Using cookie scoop, place dough onto cookie sheet and ensure they are evenly spaced.
Place cookie sheet(s) in oven and bake for 10 minutes.
Allow cookies to cool before serving.