Pre heat oven to 350. Line baking sheet with parchment paper.
Add butter, egg yolks, milk powder, and sugar to mixer, and cream for 1 -3 minutes until is light and fluffy.
Add Vanilla, and mix for another 1 minute.
In a separate medium sized bowl add the flour and the salt, and whisk together.
Slowly add about ⅓ of the flour to the butter/sugar mixture. Mix until it is just incorporated about 30 seconds.
Repeat the above directive until all the flour is fully incorporated. Mix for another 1 minute.
Rip 2 large pieces of parchment paper.
Place one of the large pieces of parchment paper out on the counter and scrape the dough out onto the parchment.
Place the second piece of parchment on top of the dough and roll the dough our over the parchment until it is about the size of a standard baking pan.
Cover tightly with plastic wrap.
Place in the refrigerator to chill for 30 min or up to 2 days. This is also where you would freeze the dough if you are making it ahead of time.
Take out of the refrigerator and roll out to about ¼ of an inch.
Use your preferred cookie cutter and place cookies on parchment lined cookie sheet.
Bake for 8-10 minutes. 8 for a softer cookie, 10 minutes for a crunchier cookie.