Combine butter, icing sugar, salt and vanilla essence, beat over medium speed until light and fluffy. Add in egg yolks in 2 batches, mix until well blended.
Combine and sieve in milk powder, cornstarch and plain flour, mix over low speed, then fold until well mixed with spatula (cover the dough to prevent it from drying).
Put some dough into piping tip (with closed star shape), use the thumb to push out the dough.
Pipe dough into caterpillar (or flying dragon) shape, put on wire rack (or baking tray) lined with parchment paper.
Dot with red colour as the eyes.
Set aside the piped dough for 2 hours until hardened before baking (this will help the cookie to maintain its shape when baked).
After 2 hours, preheat oven to 160°C/320°F.
Bake at 160°C/320°F for 15 minutes (turn the tray once after baking for 8 minutes). Set aside to cool completely after removing from oven.
Video
Notes
This recipe yields 95 pieces of cookies.The nutritional value for reference is for 1 piece of cookie.