In a large bowl or stand mixer, cream butter and sugar until light and fluffy. Beat in egg yolks and vanilla until well-mixed. Add flour and salt, scraping down bowl occasionally. Cover bowl and refrigerate at least 3 hours or overnight.
Once chilled, roll out dough with a rolling pin, being sure to flour the pin and surface. Use cookie cutters to cut into shapes. Bake on parchment paper covered cookie sheet for 9 minutes at 375 degrees.