In the bowl of an electric mixer, combine cornstarch, sugar and salt.
Mix until combined.
Add vanilla extract, egg yolks and coconut.
Mix until thoroughly combined.
Add butter and mix until all the butter chunks have softened into the cornstarch.
By hand, knead for a few minutes. If there are any butter chunks, soften it in between your fingers and the cornstarch.
The dough is quite crumbly, but the heat of your hands will help mold the cookies, so don’t be concerned.
Cover and leave to rest for 15 minutes.
Preheat oven to 350 F.
Line 2 cookie sheets with parchment paper and spray with non stick spray.
Shape cookies into discs about 3” in diameter and ½” thick and place on the cookie sheet, leaving about 2 inches space in between each cookies.
When the cookie dough starts to stick to your hands too much, lightly dust your hands with a little cornstarch and continue to shape the cookies.
Using the tines of a fork, press down slightly in the center of the cookies.
If the cookies crack when you do this, use your hands to smooth out any of the cracks.
Place in oven and bake for 20-25 minutes, until they feel firm on the top.
Remove from oven and leave to set completely, about 10 minutes.
Using a spatula, remove the cookies from the cookie sheets.