Mix eggs and milk. Season with salt and nutmeg. Wash the chives, dab dry, cut into fine rolls and add. Grease a flat ovenproof dish (approx. 8x10 cm; approx. 1/2 litre capacity). Pour in egg milk and let it stand in a hot water bath for 20-30 minutes. Turn out of the mould and cut into rhombs. Meanwhile peel and finely chop onion and garlic.
Heat the oil in a pot. Sauté onion and garlic in it. Add tomato paste and let it sweat. Deglaze with stock and tomatoes and bring to the boil. Season to taste with salt, pepper and chilli powder. Arrange the soup and the eggs on plates and serve sprinkled with chives as desired