Place the potatoes in a large saucepan with a pinch of salt. Pour in enough water to cover the potatoes. Bring to a boil and drain when tender, after about 20 minutes.
Cook the bacon in a frying pan and drain on paper towels.
Chop the onion into small cubes and chop the garlic finely.
In the same pan, add a little butter. Sauté the onion and garlic until translucent.
Add the spinach and sauté until wilted. Season with salt and pepper.
Mash the potatoes with a potato masher and add the crème fraîche while mashing.
Add the spinach and bacon to the mash. Season to taste with salt, pepper and nutmeg.