Overnight biga:
First combine your overnight biga ingredients in a small bowl. Stir it all together until there are no dry spots of flour. Cover the bowl with plastic wrap or a clean kitchen towel and leave it on the counter overnight or at least 4 hours. 

Ciabatta bread dough:
In the bowl of your stand mixer or a large bowl, weigh out all of your dough ingredients and also add in all of your overnight biga. If you're using a stand mixer, knead on medium or medium-low for 8 minutes, until you have a slightly sticky but smooth dough. If you are kneading by hand, you will need to knead on your counter or board for about 10 to 15 minutes until you get a smooth dough.

Once your dough is formed, add it to a lightly oiled bowl and let it rise, lightly covered in a warm spot in your kitchen for 1.5 to 2 hours. 

Green onion and Parmesan cheese filling: after 1.5 to 2 hours, your dough should have doubled. Remove it from the bowl to your counter and flatten it out into a rough rectangle shape. Sprinkle almost all of the Parmesan cheese (hold back about 2 tablespoons worth for topping). Sprinkle almost all of the green onions on top of the cheese (reserve just a little bit, maybe 2 teaspoons, for topping). 

Pretend your rectangle is a letter and fold it up into thirds. Turn your "letter" 90 degrees on the counter, press it into another rectangle, and fold it in thirds again. Place the dough back into your bowl. The folding process you just did adds structure to your bread and ensures the cheese and green onions get distributed evenly. 

Let the dough rise again in a warm spot for another 45 minutes. 

After 45 minutes, it is time to shape the ciabatta sandwich rolls. Remove the dough from the bowl to the counter and form it into a rectangle. 

For smaller-sized rolls (8 rolls):
If you want smaller rolls, form the dough into a rectangle 12 inches across by 8 inches tall. Using a ruler, cut the dough into 3-inch x 4-inch rectangles. If you don't want to measure, just cut your rectangle into 4 rolls across by 2 rolls tall.

For longer/larger rolls (6 rolls):
If you want larger rolls, form the dough into a rectangle 9 inches across by 10 inches tall. Using a ruler, cut the dough into 3-inch x 5-inch rectangles. If you don't want to measure, just cut your rectangle into 3 rolls across by 2 rolls tall.

Once you've got your rolls cut into rectangles, add them to a parchment-lined sheet pan and let them rise covered with oiled plastic wrap or a clean kitchen towel for 1.5 hours. 

Pre-heat oven to 425°F (220°C)

Before you add the rolls to the oven, spray them liberally with water from a spray bottle. If you don't have a spray bottle, you can lightly spread water on each roll with your fingers. Sprinkle the rest of the reserved Parmesan cheese and green onions on top of each roll for topping/garnish.

Bake 20 to 25 minutes or until the ciabatta is golden. Rotate the pan halfway through the cooking time for even browning.