What a find! These cookies are so much like our family's traditional Christmas Linzer Torte, which is a beast to make. There are so many advantages to having it all in cookie form, but I won't enumerate them here.
So, taking from our recipe, I added 1 -2 T. rum, and about 1 T cocoa powder. Hazelnuts are THE nut to use if you possibly can. I chilled the dough overnight and found it very easy to handle.. Everything else is the same. Regarding the jam filling: melt the jam and put just enough on bottom cookies to cause them to stick together, else it could be runny.
Thank you, Baking Girl!!