1. First, use the machine to beat the butter mixture. After that, the butter will turn white and feel a little solidified.
2. Sift the dried yolk. When sifting, squeeze it with a spoon. I feel that the dried yolk is easier to sift
3. Machine the mixture of egg yolk and butter.
4. Sift the flour mixture into the mixture of butter and egg yolk, mix well, and knead into a dough.
5. Wrap the dough with plastic wrap and refrigerate for about 1-2 hours.
6. Take out the refrigerated dough and rub it into small round dough (about 1-2cm in diameter) and put it on the baking tray, with a gap of about 3cm between each dough
7. Press the dough with a small spoon to make it naturally crack. The thumb is OK, but I think it's better to press it with a spoon
8. Use a fork to poke some holes in the dough. It's ok if you don't, but it's pretty good.
9. Place in an oven preheated to 320 degrees Fahrenheit (170 degrees Celsius) and bake for 15-20 minutes.