Focaccia with biga THOUSAND BUBBLES

Hi, today I propose you a delicious and really simple recipe: focaccia with biga mille bubbles. To be enjoyed plain or with cold cuts and cheeses, come with me to the kitchen to see how to obtain a truly irresistible focaccia!
Ingredients:
Biga
400g of 0W320 flour
180g of cold water (45% water)
4g of fresh brewer's yeast (1.5g if you use dry yeast)
Refreshment:
150g of 0W320 flour
200g of cold water
15g of salt
6g of malt
20g of extra virgin olive oil