Finely crumble the bread. Heat butter in a pan. Fry the bread crumbs in the pan until golden brown. Take out. Clean the leek, wash thoroughly and cut into fine rings.
Cook the pasta in plenty of boiling salted water according to the instructions on the packet. Heat the oil in a pan. Fry the diced ham until crispy, turning it over. Remove. Steam leek in hot frying fat for about 3 minutes.
Add ham to the leek. Dust everything with flour and sauté briefly. Deglaze with 300 ml water and sour cream. Bring to the boil, stir in horseradish and simmer for about 3 minutes. Season to taste with salt and pepper.
Drain the pasta, let it drain and put it back into the pot. Mix immediately with the horseradish cream. Serve and sprinkle with the breadcrumbs.