1. Fill bowl of electric mixer with warm water, and let stand for 2 to 3 minutes.
2. Empty the water and wipe with a dry kitchen towel.
3. Using the paddle attachment, starting on low speed, cream the Plugrá Butter until smooth, about 1 to 2 minutes, scraping down the side of the bowl as needed.
4. Add the sugar and continue to mix until well blended, about 2 minutes.
5. Reduce the speed to low, add the flour and mix just until the mixture forms a soft dough.
6. In a small mixing bowl, whisk together the egg yolks and vanilla extract. Then add them to the butter mixture, mixing on medium speed for about 1 minute, scraping the sides of the bowl.
7. Mix half the flour into the Plugrá Butter mixture, mixing on medium speed for about 1 minute, then add the remaining half and mix until just combined, about 1 more minute.
8. Remove the dough from the electric mixer, wrap in plastic and refrigerate until firm, about 1 hour.
9. Line 2 baking sheets with parchment paper.
10. Divide the dough into 4 equal pieces and work with one at a time, keeping the others refrigerated.
11. Lightly dust a work surface with flour. Turn one piece of dough out on the work surface. Dust your hands or a rolling pin with flour and flatten or roll the dough to about 3/8 inch thick.
12. Using a cookie cutter, cut out the cookies and place them about 1-inch apart on the parchment-lined baking sheets.
13. Repeat with the remaining pieces of dough. Gather the scraps together into a loose ball, refrigerate until firm, about 1 hour and reroll.
14. Preheat oven to 325°F.
15. Bake the cookies until they are firm to the touch and lightly golden brown, about 12 to 15 minutes.