Preheat the oven to 35 °. Warm milk lukewarm (!), Crumble in yeast and dissolve completely while stirring. Put the flour in a bowl, make a large hollow in the middle, pour in the yeast milk, add 1 teaspoon of the sugar and mix both with a little flour from the edge until liquid. Close the bowl and place in the warm oven for 15 minutes. After that, the yeast mixture is said to have doubled and small bubbles formed. In the meantime, line the tray and a base with baking paper or foil.
Add the remaining sugar, salt and butter and knead everything with the dough hook of the hand mixer until you have a smooth, non-sticky dough. It should be elastic and easy to roll out. Then divide the dough into 2 equal portions, shape each into a ball and then roll out both about 32 cm round and about 5 mm thin. Divide the two sheets of dough into 8 segments and roll them out individually with a rolling pin to make them even more pointed and wider at the top until they are approx. 4 mm thick. Then roll up the triangles from the upper broad side. The tips should end up just below the rollers. Then place 8 pieces at a distance on the sheet and base and bend them like a horseshoe. When everything is done, cover the tray and base with a cloth and let the croissants rest and rise for 2 hours.
Preheat the oven to 200 ° O / bottom heat. Whisk the egg yolk with the milk and brush the first 8 croissants twice with it. Slide the tray into the oven on the 2nd rail from below. The baking time is 12 - 15 minutes. They should get a golden brown color and have risen again well during baking. When the first batch is baked, remove the foil including croissants from the tray and pull the second prepared one on top with the other 8 pieces, also brush the egg twice and bake as before.
They are so small portioned on purpose. But if you like it bigger, you can divide the dough sheets into 6 or even 4 parts. The dough can be rolled out very well without flour and is very easy to shape thanks to its elasticity.
The croissants taste good with a sweet, but also with a hearty topping.