1. Preheat the oven to 300-degrees.
   
   

2. Separate egg, placing white in a small bowl. Place walnuts in another small bowl.
   
   
3. Cream butter and brown sugar.
   
   
4. Add egg yolk and mix. Gradually add the flour while mixing.

5. Form dough into small balls about one-inch in diameter.
   
   

6. Dip first in unmixed egg whites, then roll in walnuts to coat.
   
   

7. Bake at 300-degrees for 5 minutes. Remove and press small indents into each cookie with a finger or thumb.
   
   If the cookies are too hot to the touch (grandmas always seem to have fingers like asbestos when it comes to cooking), you can use the back of a small melon baller--it works equally well.
   
   

8. Return to oven and bake for an additional 15 minutes. Do not overbake; cookies will not brown.
   
   
9. Remove from the oven and immediately fill the indents with the fruit jelly.
   
   
10. Place cookies on a rack to cool.

Finished product with apricot and cherry fillings.

Rolling dough in ground walnuts.

Pressing "thumbprints" into cookies.

I never saw my grandma use anything other than Solo brand fruit fillings, so never do I.

NOTE:   To store for more than a few days, stack between layers of wax paper to keep jelly centers from sticking to each other and then refrigerate or freeze. Bring to room temperature before serving.