Peel, wash and chop the carrots and potatoes. Cook the potatoes in salted water for about 20 minutes, and add the carrots for the last 10 minutes.
Hard boil eggs, quench and peel.
Finely dice the onion and sauté in 2 tbsp. of butter. Dust with flour, sweat and stir well with 250 ml water and 250 ml milk. Bring to the boil, stir in the soup cubes and simmer for 5 minutes. Stir in mustard.
Season to taste with salt and pepper. Keep warm.
Drain the potatoes and carrots. Heat 250 ml milk and 1 tablespoon butter. Add to the vegetables and mash them. Season with salt and nutmeg. Serve, add halved eggs to the sauce. Sprinkle with pepper.