1. Wash and trim the celeriac; cover with cold, salted water in a pan with the lemon slice. Simmer, covered for about 50 minutes until almost tender; drain, peel and slice.
2. Melt the butter in a clean pan, add the celeriac with a little lemon juice; cover and cook for 8 - 10 minutes, shaking the pan occasionally.
3. Take from the heat and add the fresh cream. Simmer gently for 5 minutes and
4. serve sprinkled with grated nutmeg.