Onions peel, onion tips cut off as a lid. Hollow out the onions. Peel and wash potatoes and cook in boiling salted water for about 20 minutes. After approx. 10 minutes add the onion scoop.
Cut the bacon into strips and leave them crisp in a pan while turning. Peel and quarter the apple, remove the core and dice the fruit flesh. Wash marjoram, shake dry, remove leaves except for something to garnish, strip from stalks and chop.
Drain the potatoes, add the milk and butter and mash them with a potato masher to form a puree. Season with salt, nutmeg and marjoram, fold in apple and bacon. Fill onions with puree and place in a greased casserole dish.
Sprinkle onions with cheese and bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 25 minutes. Arrange, garnish with marjoram and add the rest of the puree.