Heat milk for the dough. Put 375 g flour in a bowl, make a depression in the middle and crumble the yeast into it. Add 2 tablespoons of sugar and lukewarm milk and mix with a little flour from the rim to form a pre-dough. Cover and leave to rise in a warm place for 15-20 minutes.
Spread butter in flakes, 50 g sugar, 1 pinch of salt and 3 egg yolks on the edge of the flour and work everything into a smooth yeast dough using the dough hooks of the mixer. Cover and let rise for about 40 minutes.
Roll out the yeast dough on some flour to a rectangle (approx. 25 x 40 cm) and cut into 6 cake pieces. Cut the cake pieces on the short side about 1 cm long each. Then roll up loosely from the short side towards the corner. Put them on a baking tray lined with baking paper and let them rise for about 30 minutes.
Whisk 1 egg yolk and 2 tablespoons of water. Spread the croissants with a thin layer. Bake in a hot oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer) for approx. 15 minutes. Let them cool down.
The Portuguese like their croissants best with cheese - such as sheep's cheese or Manchego - and Serrano ham.