For the puree, peel and quarter the potatoes, put them in a saucepan with salt and enough water to cover them. And about 18 minutes. Drain the potatoes, add the hot milk and the butter to the potatoes and use a whisk process into puree. Season with salt, pepper and nutmeg. For the spinach: peel the onion and cut into small pieces, put the bacon in a saucepan and fry with the onion, add the spinach and bring to the boil. For the sauce: put the cream in a saucepan and add the parsley, season with salt and pepper. Fry the fish fingers in a pan with a little oil on both sides until golden-yellow. Serve the puree with the spinach and the fish fingers with the sauce.