For the vegetable pasta casserole, boil the penne in salted water until soft. Cut onion into small cubes and fry briefly. Dice the remaining vegetables.
Whisk sour cream and eggs and season with salt, basil and oregano. Mix in pasta. Pour the mixture into a greased and crumbled baking dish.
Cover with mozzarella and bake the vegetable pasta casserole at 180°C top-bottom heat for about 45 minutes.