In a bowl, dissolve the yeast with 50 ml warm hay milk (at no more than 30 °C). Add 40 g of flour and mix with a spoon until you get a dough. Cover with a dish towel and let rise for 30 minutes.
Add the remaining flour, sugar, remaining milk, eggs, orange zest and vanilla.
Knead the dough with the kneading hooks for 8 minutes until smooth and homogenous.
Continue to knead, add salt and gradually incorporate the soft butter in small pieces.
Knead the dough briefly, place it in a bowl, cover it and let it rise for one hour at room temperature.
Using a scale, separate the dough into 9 portions, each 100 g, and shape into balls.
With the help of a little flour on the work surface begin to stretch each ball of dough, rolling it with your hands until you obtain a string about 50 cm long. Wrap the two ends together and fix them on the central part of the string in order to obtain the classic pretzel shape.
Place the pretzels on a baking tray lined with parchment paper, cover with a tea towel and leave to rise for another hour in a warm place.
Mix the egg with 2 tablespoons of milk and coat the pretzels.
Bake in preheated oven at 200°C (or 180°C convection) for 16-18 minutes.
Coat the pretzels with melted butter while still hot and turn them in powdered sugar.