Cut the bacon into fine cubes and leave it in the pan. When the bacon starts to turn translucent, add the finely chopped onion and keep leaving it out until the onions are golden yellow.
Mix the blood and milk roll mixture. Let the onion and bacon mixture cool down a little, add and stir well. Season with salt, pepper and marjoram and place in a flat baking dish.
Let it set in the oven at 200 degrees for about 30 minutes. Put flakes of butter on top and let cook for another 10 minutes. A nice brown crust forms.
There is also sauerkraut and boiled potatoes.
Note: It is important that the blood is bought from a butcher who can be trusted and is passed through a fine sieve one more time.