In a bowl combine room temperature butter and powdered sugar. Mix for 4 minutes on medium high speed until pale and very creamy.
Add the blood orange zest, vanilla, salt, and egg yolk and continue to mix for an additional minute.
Sift the cornstarch and flour over the bowl of the butter and sugar, then combine using a spoon or spatula. It will form a soft dough.
Fold in the finely chopped roasted pistachios.
Using a tablespoon or ¾ounce cookie scoop, portion out the dough on a parchment lined baking sheet. There will be 24 cookies.
Using a half teaspoon measuring spoon or your thumb, make a one inch deep indention in the tops of the cookie dough.
Place cookie dough in the fridge for at least an hour and up to overnight.
When ready to bake the cookies, preheat the oven to 325*F.
Fill the indentions of the cookies with a half of a teaspoon of blood orange curd.
Bake 12 cookies per parchment lined sheet pan at a time for 13-14 minutes. The cookies will look set and the bottoms should be barely golden. The blood orange curd will appear jiggly but will set up as it cools.
Allow the cookies to cool for 20-30 minutes before dusting with powdered sugar.
Enjoy!