Peel the potatoes, cut into cubes (approx. 1.5 cm) and steam them or boil them as boiled potatoes.
Heat 1 tablespoon butter in a saucepan, fry the meat sausage pieces and the onion rings for 3 minutes. Then add the pepper cubes and cook for another 2 minutes. Mix with the cooked potatoes and pour into a greased casserole dish.
Heat 3 tablespoon butter in a saucepan, stir in the flour and let it froth. Deglaze with milk and stock, simmer for 5 minutes while stirring and season. Pour half of the cheese into the sauce, pour over the potatoes and sprinkle with the rest of the cheese.
Bake in a preheated oven at 180 ° C for a maximum of 20 minutes.