In your food processor, grind the hazelnuts and flour together until fine. Alternatively, you can use a Ziploc bag and rolling pin if you lack a food processor.
With your stand mixer and paddle or hand mixer and beaters, cream together the butter and sugar until light and fluffy.
Add the eggs and zest, and mix until combined. Scrape down the sides of the bowl and attachments.
Add in the hazelnut/flour mixture with the spices and salt, and mix until incorporated. Scrape down the sides of the bowl and attachments and mix for another minute.
Wrap and refrigerate the dough for at least 30 minutes.
Preheat the oven to 350°F, and line a sheet pan with parchment paper.
Flour a working surface, and roll the dough 1/4 inch thick. Cut with a 2" Linzer cookie cutter remembering you need both a top (with the window) and bottom (whole cookie). Reroll the dough until you use it all up, but make sure you have and equal number of tops and bottoms.
Place the cookies on your prepared sheet pan about 1/2 inch apart and bake for 12-14 minutes rotating halfway through. The cookies should a light golden brown colors on the edges. Be careful transferring the tops; you don't want them to warp.
Once the cookies are cooled down, spread with jam and sandwich. When spreading the jam leave about 1/4" ring around the edges. When you sandwich it will help prevent any leakages. Dust with powdered sugar.