Source: Nourishing Traditions, Sally Fallon

Ingredients

6 baked potatoes
3 celery roots, peeled and cut up
2 cloves of garlic, peeled and mashed
pinch of nutmeg
sea salt and pepper
1/2 cup butter 
1/2 to 1 cup piima cream or creme fraiche

Directions

Cover the celery root pieces with cold water, bring to a boil and cook until every tender, about 30 minutes. Cut up the butter and place in the bottom of a large bowl. Scoop out potato flesh into the bowl. Add celery root and garlic, and mash all together. Add the cream to obtain the desired consistency. If you want your puree really smooth, you can now mix with a handheld beater. Season to taste. Transfer to a buttered ovenproof dish and keep warm in the oven.