Insert the milk, flour, sugar, yeast, and add the egg, starting to knead at speed 3 for about 5 minutes. During the kneading, add the water gradually. After the first 5 minutes, add the salt and continue kneading for another 5 minutes at speed 8/10, then incorporate all the soft butter, allowing it to absorb, and finish the kneading.
Once the kneading is done, remove the dough from the machine and let it rise in a previously greased bowl. Let the dough rest (bench) for about 30 minutes, then form balls weighing 100/110 g each. Place them on a baking tray lined with parchment paper, spaced apart, and cover them with another sheet of parchment paper, then cover with another tray; this way, they will flatten.
Let them rise for about 1 hour. Brush with a mixture of egg yolk and milk, sprinkle sesame seeds or poppy seeds on top, and bake at 170/180°C for about 20 minutes.
