Place the slices of bread on a baking tray lined with baking paper.
Bake for approx. 30 mins. in an oven preheated to 160 °C until the bread is dry but not brown. Remove, allow to cool slightly, blitz in a food processor.
Mix the flour, semolina, salt and yeast in a food processor bowl. Pour in the water and oil. Using the dough hook on a food processor, knead into a smooth, soft dough for approx. 5 mins. Cover and leave to rise at room temperature for approx. 3 hrs.
Tomato & onion sauce
Make cross-shaped incisions into the tomatoes and blanch in hot water for approx. 30 secs. Remove, refresh the tomatoes in ice-cold water, drain, peel away the skin and cut into quarters. Heat the oil in a pan. Cover the onions and steam for approx. 10 mins., stirring occasionally. Add the tomatoes and garlic, cover and simmer for approx. 15 mins., stirring occasionally.
Brush a baking tray with oil, place the dough on the tray, press down gently by hand, pull into shape, cover and leave to rise for a further 30 mins. Spread the anchovies and 1/4 of the cheese on top. Add the tomato & onion sauce, scatter the remainder of the cheese, oregano and breadcrumbs over the top, drizzle with oil.
Approx. 25 mins. on the bottom shelf of an oven preheated to 240°C.