Cook the potatoes in plenty of boiling water for about 20 minutes, then let them cool down and peel them
Grease a baking dish. Preheat the oven to 200 ° C top / bottom heat, circulating air 175 ° C.
Melt the fat in a saucepan. Add the flour and sauté briefly. Pour in the broth and cream while stirring. Bring to the boil, cook for about 3 minutes and season with salt and pepper.
Peel the carrots and kohlrabi. Cut the carrots into slices and the kohlrabi into cubes. Wash the parsley, shake dry and finely chop except for something to garnish. Stir the cheese, except for something to sprinkle, and the chopped parsley into the sauce. Dice the potatoes.
Put the potatoes, carrots and kohlrabi in a greased baking dish. Pour the sauce over and sprinkle with the rest of the cheese. Bake in the preheated oven for 30-40 minutes.
Garnish the casserole with parsley and serve immediately.