Prepare the dough by mixing all above ingredients, apart from the butter (or marg.). The dough comes out sticky, so it’s a good idea to grease the work surface first.
Cut the dough with a knife, into four equal portions.
Divide the butter into 12 cubes of 25gr. each.
Roll the first piece of dough into a square, or circle, and press small blobs of the butter cube on the top 2/3 of the dough. Fold the bottom 3rd of the dough onto the middle and fold the top 3rd down on top of that, to form a rectangle. Repeat this sequence from the sides – first fold the right-hand 3rd of the dough to the middle, then the left-third of the dough on top to form a square. Put the square aside.
Repeat these steps for all remaining portions of the dough. Wait 15 minutes and repeat all steps for all portions.
Wait another 15 minutes, roll out the squares, and repeat a third time to all squares.
Place the dough squares into a nylon bag, tie it closed, and leave them to rise in the refrigerator overnight (minimum time for rising is 4 hours).
Roll out the first piece into a flat circle of dough, and slice it into 4 quarters. Slice each quarter into an additional 2 or 3 slices (like pizza). You should end up with 8 or 12 (thin) triangular slices.
Starting from the wider end of each slice, roll it inwards towards the center of the circle to form a small croissant. Place it on a lined baking pan.
For chocolate croissants: Slice the circle into 12 triangles, and place two cubes of bittersweet chocolate at the edge of the slice before rolling it
After shaping all the croissants, wait about an hour before placing them in the oven at 200C.