Pasta is cooked in salted water, drained and without rinsed with cold water, is poured over one half of the butter, highly preheated. In the remaining butter fry until golden finely chopped onion and salted. Drain of the butter and set aside. In the butter put peeled and finely chopped tomatoes, add salt and gently sauté ten minutes. Pasta partitioned and each added a bit of onion and tomatoes. Top put the grated feta cheese.