Tian of Tomato, Courgette and Fennel with Roquefort

• 6 tablespoons olive oil
• 1 onion, thinly sliced
• 1 garlic clove, crushed

A tian is a Provençal earthenware dish suitable for all manner of gratins. Any large, shallow baking dish would be fine.

Preheat the oven to 180°C/350°F/gas mark 4. Heat 3 tablespoons