Potato and vegetable gratin

In a large saucepan with salted water, boil potatoes for about 15 minutes until just tender.

Preheat oven to 180 C / Gas 4. Grease a baking dish.

Meanwhile melt 2 tablespoons of the butter in a large frying pan and saute onions till soft. Add courgettes and cook for 5 minutes. Season with herbs, salt and pepper and fry for another minute.

Drain potatoes and add to the pan along with the tomatoes. Stir to combine with the potato mixture. In a bowl mix together Gruyere and Parmesan. Combine half of the cheese mixture with the vegetables and transfer everything into the baking dish.

Melt the remaining 2 tablespoons butter and mix with the breadcrumbs and the rest of the cheese. Sprinkle mixture over the vegetables and potatoes.

Bake gratin for about 15 to 25 minutes, until the topping is nicely browned.