In a bowl, add the unsalted butter at room temperature, and beat using an electric mixer for 1 minute.
Add the refined sugar and the egg yolks, beat well until combined.
Add the cornstarch, the vanilla powder and the baking powder, beat well.
Gradually add the wheat flour and keep gently mixing with a spatula or spoon until a smooth dough forms.
Now, cut the top off a wide neck bottle. Using a pen, draw a zigzag pattern on the lid, then using a hot knife, make cuts in the shape of the drawing, just like shown in the video.
Once you’ve done that, fill the neck of the bottle with some dough, and on a baking sheet lined with nonstick baking paper, press on it with your fingers, passing the dough through the lid you just cut.
Do it until a dough strip about 10cm long is formed.
Place a piece of milk chocolate on the tip of the dough strip, fold the dough over the chocolate and cut off the excess dough with a knife.
Repeat this process with all the dough.
Finally, take to a preheated oven at 150°C (302°F) and bake for 25 minutes.
Sprinkle some icing sugar all over the biscuits and serve.