Cream together the butter & brown sugar. Once fluffy, add the egg yolks and vanilla, then set the mixture aside.
Sift together the flour and salt. Add dry ingredients to creamed mixture just until well blended.
Roll into 1" balls, and then roll the balls in finely chopped pecans.
Bake on an ungreased cookie sheet for 5 minutes, open the oven and press a thumb (or a spoon) into the center of each cookie, then return to the oven.
Bake for 8 more minutes, let cookies cool on racks.
Add your favorite flavor of jam (I use cherry, apricot, and raspberry) OR butter cream frosting to the thumb print area (you can use food coloring to tint the frosting into festive colors).
