Put 15 g of the butter in a large saucepan and heat on high. When the butter melts, add the spinach to the pan and steam for about 3 minutes on a high setting, stirring regularly. As soon as the spinach has collapsed, place it in a colander and drain. Ideally place in the open window.
Put the rest of the butter (100 g) in a saucepan and heat over medium heat. Add the finely diced onions when the butter has melted and cook for about 6 minutes until the onions are soft. Now add the clove for 2 minutes, let it steep over medium heat and remove it again.
Then add the garlic and flour and sauté for 2 - 3 minutes on medium heat, stirring constantly. Then slowly add the cold milk, stirring constantly, and let it simmer. Now increase the temperature and as soon as the mixture sets, reduce the temperature immediately (it is best to take the pan off the stove for a short time until the plate has cooled down a bit) and reduce it for 10 minutes on a low level. Stir occasionally. Season with salt, pepper and nutmeg. When the sauce is nice and thick, turn the temperature down and keep it warm.
Place the drained spinach between several layers of kitchen roll and squeeze it out vigorously (the less water it contains, the better the recipe works).
Just roughly chop the dry spinach, add to the sauce in the saucepan and carefully fold in.