Place the cranberries, sugar and 100ml (0.4 cups) water in a saucepan and bring to the boil. Cook for about 10 minutes until the cranberries are soft and you have a nice jam. Leave to cool. Alternatively, you can use ready-made cranberry jam.
Finely chop the onion. Fry the onion in a small knob of butter on a very low heat for about ten minutes until glazed. Leave the onion to cool on a plate in the fridge. Finely chop the buttered slices of bread.
Place the mince in a large bowl with the onion, egg, bread slices and garlic powder. Season to taste with salt and pepper and knead well. Make small balls. Turning the balls is easier with wet hands. So place a bowl of water where you can moisten your hands every few balls. Make sure they are all the same size. I do this by weighing them on a scale, 10 grams (0.3 oz) at a time, but I totally understand if you don't feel like it and want to do it by feel ;)
Meanwhile, peel and halve the potatoes. Bring the potatoes to the boil in a large pan of water. Cook the potatoes until tender and drain. Leave them to drain in the pan for a while. Heat 100g (3.5 oz) of butter and the milk in a pan. Mash the potatoes together with the butter and milk mixture. Season with salt, pepper and nutmeg.
Fry the meatballs in a knob of butter until golden brown. Add a heaped tablespoon of flour and 25g (0.9 oz)of butter. Fry the flour and butter for a while. Pour in the stock and cream and cook until the sauce thickens. Add the Worcestershire sauce and mustard and stir. Season with salt and pepper and sprinkle with finely chopped dill.
Notes
I've calculated the nutritional value for four servings, but you probably won't use all the cranberry jam, so it's a bit trickier. So this is just a rough estimate... 🙂