1. In a large volume of salted water, cook the penne al dente. Preheat the oven grill.

2. Cut and rinse the turnip greens. Coarsely chop. Wipe and slice the mushrooms.

2. In a saucepan, sauté the mushrooms in butter, over medium heat, until the water evaporates.

3. Add the turnip greens, salt, pepper, reduce heat and let the greens wilt. Add the broth. Bring to a boil, simmer for about 2 minutes.

4. Drain the penne. Add to the vegetables in the saucepan and mix well. Pour the pasta into a gratin dish, sprinkle with chopped hazelnuts and grated Emmental.

5. Place the dish under the oven grill and let it brown. Serve.