1. Place the celeriac and potato dices into a big pot and cover with cold, salted water.
2. Bring to the boil and simmer for 15 minutes until cooked through.
3. Drain and return to pot. Add the cheese, butter and milk then season with salt, pepper and nutmeg. Mash with potato masher until you reach your preferred texture.
4. Heat a little olive oil in a non-stick frying pan over medium heat. Add salmon cutlets and cook for 2-3 minutes each side or until cooked to your liking. Serve on a bed of potato & celeriac mash.