Peel the onion and sweat it in a frying pan with a dash of extra-virgin olive oil. Add the tomato passata and cook over a low heat for about 15 minutes.
Cut the broccoli, tomatoes and courgette into thin slices. Spread the tomato passata onto an oven dish and arrange the vegetables on top. Add salt and pepper to taste. Roast for about 10 to 15 minutes.
Take the tray out of the oven, add the 4 eggs and put it back into the oven for about 10 more minutes. If you like, grate some Emmental cheese on top to finish the dish off au gratin.