Stir flour and salt together in a bowl.
Beat butter and sugar together with an electric mixer.
Add egg yolks, vanilla and flour to the bowl of the mixer and beat until well blended.
Roll dough into balls.
Beat egg whites with fork.
Dip dough balls into egg whites, then into chopped pecans.
Place on ungreased cookie sheet and press thumb into each cookie to make an impression.
Bake at 375 degrees for 12-15 minutes.
Fill with teaspoon of Hershey's Spreads. Sprinkle with a bit of kosher salt.