1. Preheat oven to 200 degrees.
2. Beat the eggs with a tablespoon of cold water. Season with salt, pepper, chopped dill.
3. Zucchini and tomatoes cut into thin circles.
4. In a thick-walled refractory pan melt the butter. Add the onion, diced. Saute until transparent.
5. On top of the bow lay circles zucchini, then tomatoes. Repeat layer of zucchini and tomatoes. Vegetables pour beaten eggs. Hold on a plate for 2-3 minutes.
6. frittata sprinkle with grated cheese and place in oven for 15 minutes.