Soften the butter and mix it with the grated parmesan cheese in one bowl. Mix the flour, baking powder, chili, and garlic powders together in a separate bowl.
Add the flour mixture to the butter mixture and work it into a dough, adding small amounts of egg to help it come together. Do not add all the egg at once, and stop before it gets wet and sticky. A little bit sticky is fine.
Turn the dough onto a piece of plastic food wrap and use that to form it into a long sausage (around 9 inches). Wrap it in the plastic cling film and roll it to even out the sides. Chill in the freezer for 15 minutes whilst the oven preheats.
How to bake the cookies
Preheat the oven to 175 C / 350 F
Take the dough out of the freezer and brush it with an egg wash before rolling it in the seed mix to form a crust.
Slice the parmesan cookie dough into thin disks 0.5cm thick and place them on a lined baking tray.
Bake the spicy parmesan cookies in the oven for 10-15 minutes until they have risen slighty and are golden brown in color.
Remove them from the oven and leave them to harden up for 10 minutes before serving them still warm.
Notes
Don't melt the butter, just soften it enough to be able to nix into a paste with the parmesan. Use a fine cheese grater or microplane for the parmesan to get as fine a grate as possible. Mix this recipe by hand; you do not need to use a food mixer. Add the beaten egg to the dough a little at a time. If you add it all, it can become too wet and sticky. Egg sizes vary around the world. I use around ¾ of a UK large egg in this recipe. The cookies will expand slightly as they bake, so don't place them too close together on the tray.You will be able to smell the cookies when they are ready. In my oven, they take 12 minutes.