Roast and peel the chestnuts. (I buy 'em in a jar already peeled.)
Cut the sprouts in 1/2.
Sautee the sprouts in a couple tablespoons of butter and one of oil until they are starting to get a little golden. (about 15 minutes) Season with salt & pepper as they're sauteeing.
Add chestnuts, continue cooking 'till sprouts are nicely brown and tender.
Add 1/2 cup vinegar, 1/4 cup sugar and 1/4 cup turkey (or chicken) stock
Cook 'till liquid is syrupy - about 5 minutes.
the potatoes, sliced thin, are boiled with cream and a little butter (not quite enough to cover) until tender. Once tender the potatoes are mashed right inside the cooking vessel and with a sprinkle of salt, ready to serve. The results are a smooth, creamy sweet potato mixture that really lets the mild flavor of the sweet potato shine.