Preheat oven to 350℉ (180℃). Brown onions in butter; add hamburger and continue browning. Drain; add tomato soup, and salt, pepper, oregano, and thyme, to taste. Place in greased 2 or 2½ quart casserole. Partially cook green beans or peas, and layer beans on top of meat in casserole. Mash potatoes and mix with milk and egg. Layer mashed potatoes on top of beans. Bake until top is brown and sides bubbling, approximately 30 minutes. Let cool for a few minutes and serve warm. Sprinkle smoked paprika and fresh parsley if desired.