Pecan Jam Thumbprint Cookies

These are a real special cookie (read: tedious and time-consuming). They look great on a Christmas cookie platter, next to a cup of tea, or with a glass of milk. Use any type of nut and jam you wish! Pictured here are pecan and strawberry. 

Pecan Jam Thumbprint Cookies
1 cup butter, softened
1/2 cup granulated (white) sugar
2 large eggs, separated
1 teaspoon vanilla extract
2 cups all-purpose (plain) flour
pinch salt
1 cup chopped pecans
jam of choice

In a large bowl, cream together the butter and sugar. Add the egg yolks and vanilla. Stir in flour and salt. Chill dough for 30 minutes.
Preheat oven to 350◦F. Line baking sheets with parchment paper.
Roll dough into one inch balls, dip in egg white, then roll in nuts Place on prepared baking sheets.
Make an indentation in the center and fill with 1/2 teaspoon jam.
Bake for 12-15 minutes until cookies are set.