Mix the egg, sugar and oil in a big bowl.
Add the milk powder and flour to the mixture, combining until a dough forms. Let rest for 30 minutes.
Bake the salted egg yolks in a small pan at 180 degrees Celsius for about 10 minutes. Cut and crush into small, powdery pieces.
Add oil, salt and low-gluten flour to the crushed egg yolk powder, combine and form a ball.
Roll out the dough from step 2, and place the egg yolk ball in the center. Wrap the ball with the dough and pinch the seams.
Roll the dough out into a flat and rectangular shape, then fold and roll out into the same shape again. Repeat three times.
Cut the rectangular dough into 3*10cm pieces, and use a fork to make a row of indentations every 2cm
Set oven to 170 degrees Celsius and bake for about 5 minutes, apply a coat of egg wash, then bake for another 20 minutes.