This is one of our all-time favorites, created by Chef Charlie Palmer.
What to buy:
Fresh is better, but good-quality frozen or jarred chestnuts are a reasonable substitute (they do not need to be roasted). For fresh mail-order chestnuts, try Delmarvelous Farms.
Slab bacon, available from most butchers (call ahead), is almost always sold with the rind still attached; cut it off before using. Put the bacon in the freezer for 20 minutes or so to firm it up before slicing.
To peel a chestnut, cut a large X into one side of the shell, cutting all the way through the tough membrane. (If you don’t, the chestnut will blow up in your oven. Imagine popcorn the size of a ping-pong ball!) Put the chestnuts in a shallow pan and bake in a preheated 325°F oven until the shells curl along the cuts and the outsides are nicely toasted (about 15 minutes). Cool slightly (they’re easier to peel while they’re still warm) and remove the shells. Rub in a clean kitchen towel to remove as much as possible of the dark, bitter membrane.
Fill a large pot with water and bring it to a boil over high heat. Add enough salt until the water is salty tasting. Prepare an ice water bath by filling a bowl halfway with ice and water; set aside. Cook the Brussels sprouts in the boiling water until crisp-tender, about 4 to 5 minutes; they will still have some bite to them. Drain the sprouts and place in the ice bath.
When cool, remove the sprouts from the ice water, halve lengthwise, and set aside. Place a large sauté pan over medium heat. Add the bacon in a single layer and cook over medium heat until the fat is rendered and the bacon is golden brown, about 10 minutes. Remove the bacon with a slotted spoon and set aside; reserve the pan drippings.
Add the onions to the pan and reduce the heat to low. Cook the onions, stirring occasionally, until they turn a deep golden color, about 8 to 10 minutes. Add the chestnuts and cook, stirring occasionally, until thoroughly heated and well coated with bacon fat, about 2 minutes.
Increase the heat to high, add the reserved bacon and Brussels sprouts, and stir well. Add the chicken broth and cover; the contents will quickly come to a boil. Reduce the heat to low and cook until the Brussels sprouts are heated through. Stir in the butter and season with salt and pepper. Sprinkle with thyme and serve.