Note 1: You can blend the hazelnuts alone if you prefer, but I found that mixing them with the flour helps to bind them together. Don't stress too much if you still have some small pieces of hazelnuts left in the mix. They'll just add texture.
Note 2: As you work the dough, you might notice that it can become quite oily. That's the oil from the nuts getting warm at room temperature. It's pretty normal. If it becomes too oily, you can simply put it back in the fridge for a few minutes to firm it up again.
Note 3: You should be able to make around 32 little gingerbread men if you use a 2.9 inches cookie cutter like I did, which will then make 16 gingerbread man sandwiches.
Note 4: You are going to have to find the sweet baking spot for these cookies. Don't cook them much longer, or they will become quite hard. If you bake them too little, they'll be too crumbly and soft.
*Nutrition information is a rough estimate per cookie sandwich.