Roast the pumpkin seeds in a frying pan without fat, turning. Chop the marjoram finely.
Remove the peel from the kohlrabi and potatoes and cut into small slices with a vegetable slicer. Mix evenly with crème fraîche and cream, season with salt and season with pepper.
Divide goat cheese into small pieces and stir in with half of the pumpkin seeds and the marjoram. Fill the vegetables evenly into a shallow gratin dish (about 2, 8 l capacity). Bake in the heated oven on the second shelf from the bottom for 75 minutes at 180 °C until golden brown.
Sprinkle with the remaining pumpkin seeds and bring to the table. It goes well with a mixed leaf salad.