You need:

For the “BIGA” / sourdough (to be prepared min. 12 hours in advance):
– 225 g flour (wheat)
– 2/3 tsp instant yeast powder
– 100 ml water, lukewarm
For the final dough:
– the BIGA from above
– 1 ½ tsp instant yeast powder (available at many supermarkets in big (500 gr), vacuum packed packages. Note: the yeast you find in little bags and tins is not of the instant variety, and needs to be used in a different way to work!)
– 200 ml water, warm
– 300 g flour (wheat)
– 1 tsp salt
– 2 tsp milk powder
– 1 tb olive oil

(tsp = teaspoon, tb = table/soup spoon)

To prepare the “Biga” (sourdough) put flour and yeast in a bowl and add the warm water. Mix it all and knead it until you have a smooth ball (the mix is very dry, but it has to be. Don’t add more water, or only a very little bit, if really necessary….)
Put a tight lid on the bowl, or cover with foil, and leave at a WARM place (not under 21 øC!) for minimum 12 hours.
The next day:
The Biga should smell sour and “prickle” a bit.
Put it in a big bowl, add the salt and the warm water, and mix with your fingers until you have a thick liquid.
Mix the flour with the yeast and the milk powder and add it slowly to the liquid while kneading. After the flour is completely worked in, add the olive oil and continue kneading for a longer time.
Put the dough in a bowl, cover it with foil and leave it to rise for min. 1 hour at a warm place.
Than put on a baking tray covered with a lot of flour (Handle it from now on very careful, to keep as much air bubbles in as possible!)
Form the dough in a rectangle, pushing the sides carefully under, until the loaf looks like a slipper (this is why the bread got its name: Ciabatta is Italian for slipper/house shoes) Sprinkle a lot of flour on top of the loaf, cover loosely with wrapping foil and let it stand again for minimum half an hour or longer at a warm place.
Meanwhile preheat the oven to 230øC. Bake the bread for 20 to 25 minutes.

Before you cover the formed loaf with foil, make sure that the complete surface is coated with flour, or the foil will stick badly to the dough later.
Obviously the taste is the best, if the Ciabatta is fresh out of the oven. If you want to prepare your bread a day before, you can put the kneaded dough overnight in the fridge, it will still rise, and form to a loaf and bake the next morning.
The dough can also be put in the deep freezer: Wrap loosely in foil directly after the kneading and freeze. When you take it out, put it without the foil in a covered bowl at a warm place, and let it defrost and rise for at least 5 hours.

Add black olives to the dough at the end of the kneading process. Cut the olives in half and dry them well with kitchen paper. Directly before adding them to the dough, sprinkle them with a little flour, to take off the rest of the moist.