Sieve the powdered sugar, cornstarch, custard powder and flour in a mixing bowl.
Use a whisk to stir the dry ingredients well.
Put the butter in room temperature. Make sure it is already soft and no longer hard.
Mix into the flour mixture.
Mix well using spatula until it becomes dough.
Use a flower tip, push the dough through it and shape into a flower.
Press the center with chocolate chips.
Bake for 12 minutes at 180°C.
Take out the cookies from the oven. Wait until it has cooled down.
Put in a jar or serve right away. Enjoy!
Video
Notes
If you don't have a flower tip, you can round the cookies and press it, just like other cookie dough.
Watch the baking process carefully, do not let it burn too dark.
Shaping the custard dough into a pretty flowers takes practice. If it is not good enough, you can always take it back and push through the tip again. You will become an expert after a while.