Cook potatoes with the skin in salted water for about 30 minutes. Cut peppers into 2×3 cm pieces.
Pre-cook in boiling water for 5 minutes, rinse and drain.
Cut onions into eighths and fry in hot oil until translucent. Wash and finely chop herbs. Whisk creme fraiche with cream and egg yolks. Stir half of the cheese into the cream mixture. Preheat oven to 175°C. Drain the potatoes and let them cool down a bit. Grease a baking dish. Peel potatoes and cut into slices.
Put a layer of potatoes in the baking dish, sprinkle with herbs, pour some egg cream on top.
Spread half of the peppers on top, pour some egg cream. Continue with potatoes and remaining egg cream. Finally, layer remaining peppers and onions. Sprinkle remaining cheese on top.
Bake the casserole in the oven for about 45 minutes.
