The previous day, around dinner time, make the poolish, which will need at least 12 hours of fermentation. Dissolve the fresh brewer's yeast in cold water in a large bowl, then add the flour and stir with a whisk to remove any lump. Cover the bowl with plastic wrap and leave at room temperature until the next day.

After 12 hours the poolish is ready: it will be full of bubbles, alive.

Scrape the poolish in a large bowl, add the flour, salt, sugar, extra virgin olive oil and start stirring, adding slowly the warm water. Knead the dough on a board but also in the bowl itself, for about ten minutes, giving time to the dough to absorb the water. It will be sticky and very soft.

Cover your hands with olive oil and form a ball of dough: place it in a bowl greased with olive oil.

Cover the bowl with a plastic wrap and let it rise at room temperature until doubled, for at least 3 hours.

After this time, always with oiled hands, gently deflate the dough and divide it into two equal parts.

Grease with some olive oil a round baking pan. Flatten out slowly one of the balls directly into the pan, giving it time to relax as you spread it to cover the pan.

Meanwhile, roll out the other half on a floured board: again use your hands and try to stretch it gradually.

Sprinkle the dough into the pan with half the sugar and top with half the blackberries, then cover with the other stretched dough and press the edged together to seal them.

Let rise at room temperature for about two hours, then sprinkle with the remaining sugar and drizzle with olive oil. Press the remaining blackberries on top and heat the oven to 190°C.

When the oven is hot, bake the schiacciata for about 20-30 minutes, until puffed, golden and sticky with the blackberry juices. Let it cool down completely before slicing it.