Makes about 4 dozens

Ingredients

• 1 cup         soft butter
• 1/2 cup      light brown sugar
• 2                egg yolks
• 2 tsp          vanilla extract
• 2 cups        all purpose flour
• 2                egg whites slightly beaten
• 2 cups        finely chopped walnuts or pecans
• 4 tbsp        red jelly or jam

Directions 

1. In a medium bowl, with wooden spoon, beat butter, sugar, egg yolks, and vanilla until smooth.
2. Stir in flour just until combined. 
3. Preheat oven to 375F.  Using hands, roll dough into balls 1 inch in diameter.  Dip in egg white; then roll in walnuts.
4. Place, 1 inch apart, on ungreased  cookie sheets.  With thimble or the handle of a wooden spoon, press centre of each cookie.
5. Bake 10 – 12 minutes, or until a delicate golden-brown.  Remove to wire rack;  cool.
6. Place 1/4 teaspoon jelly/jam in centre of each cookie.  (Diced candied fruit may be used, instead of jelly, if desired)

I have used plum jam