Cut the peppers into small pieces and collect them in a bowl. Slice the onion thinly and brown in a very large pan with 3 tablespoons of oil and a knob of butter. When it starts to sweat after 3-4 minutes, add the peppers and sauté over high heat, so that they are roasted and remain crispy. After 4-5 minutes, add the pitted and coarsely chopped olives. Season with salt to taste. Chop the bread with a knife, reducing it to large crumbs. Dress with 4 tablespoons of oil, a spoonful of chopped fresh herbs and cook in another pan for 3-4 minutes. Add half of this bread to the pan with the peppers, along with 2 tablespoons of grated Grana Padano cheese, and stir. Transfer the vegetables to a serving dish and finish with the rest of the herbed bread.