Celery Root Puree (Mf)

Yield:	4 Servings
Categories:	Main Dishes, Side dishes

4	tb	Unsalted butter
1		Onion, finely chopped
2	lb	Celery knob
1	md	Boiling potato, peeled and diced
1/4	c	Heavy cream (or more), or
2	tb	Butter (or more), to taste
2	tb	Chopped parsley
		Salt and freshly ground pepper