Beat room temperature butter, salt, powdered sugar, and vanilla extract with an electric mixer until mixture is very pale and fluffy.
Add egg yolks and beat until mixture is homogenous again.
Add flour and mix until fully incorporated.
Roll out dough into discs approximately 1/4" thick. Cover with plastic and chill in the refrigerator at least 30 minutes but up to overnight.
When ready to bake, preheat oven to 350 degrees F.
Take the dough out of the fridge and cut out your desired shapes. Leftover dough can be rerolled a couple times for more cookies.
Bake for 15-20 minutes, depending on the size of your cookies. The longer you bake, the crispier your cookie will be, but be careful not to it burn. If you prefer a softer crumb, bake until just barely golden.
Let cookies cool and frost with icing or buttercream of your choice, or eat plain! Cookies will save in an airtight container at room temperature (without frosting).