Soften the butter at room temperature. I leave it out for about 30 minutes. You should be able to easily mash it with a wooden spatula or the back of a spoon
Mash the butter and then add icing sugar and combine until the icing sugar is no longer visible. Add vanilla and egg yolks (I highly recommend you actually weigh the egg yolks as this determines the consistency of the cookie dough) and stir again to combine until creamy. Sift in the dry ingredients. Combine until you get a soft dough and slightly sticky. The dough needs to be soft enough so you can pipe through the nozzle
If you want to color the dough, divide the dough into two and put a small drop of color on one of them and knead the dough to even out the color
Pipe the cookies:
Line a large baking sheet with parchment paper. Make sure you use a durable piping bag. I use a reusable piping bag like this. It's very sturdy. The cookie dough is not as fluid to pipe, but it should be pipeable with a slight resistance but not super hard to pipe. It shouldn't be too fluid (it will lose its shape during baking)
If it is too hard to pipe, like you have to really squeeze and still can't come out, the dough is too hard. Add a bit more egg yolk, teaspoon by teaspoon and combine well until you get the dough consistency that is soft enough to be pipe
I use Wilton 1M tip because I think it makes rougher scales(more "crackly") compared to when I use Wilton 4B. My son said it looked more like a dragon (though he still thinks it's more like a snake than dragon LOL). Anyway, it's up to you.
Pipe almost like an "S" letter. You don't want to pipe too long as it will look more like a snake. You can pipe about 1/2 inch apart, the cookie spread a little but not a whole lot
Chill in the freezer:
After you are done piping, chill the whole tray inside the freezer (yes,freezer) for at least 30 minutes. 15 minutes before the end of time, preheat the oven to 320 F (160 C). Put the tray in the middle of the oven and bake for 15-18 minutes. The cookies shouldn't brown much, just slightly golden brown at the bottom
Remove from the oven and let them cool on the tray for 10 minutes before you transfer to a cooling rack to let them cool down completely. Dip the blunt tip of a toothpick in a red food coloring to dot the eyes
Store:
They can be kept in air-tight cookie jar or container for weeks at room temperature