Because there's no fat in the dough, it's best to bake them on sprayed parchment paper.
Traditional pfeffernüße are usually hard after they've cooled - then stored for a few weeks in loosely covered tins. During this time, the spices develop a full flavour and the flour absorbs moisture, making them edible.
I can't wait for weeks, so this recipe produces ready to eat cookies. Simply dust with powered sugar while still hot and cover them while they cool.