When I told Amanda about this dish, she asked, "Don't the breadcrumbs burn in the oven?" The answer is no, but just barely. They do get very brown and crisp, as do the pancetta, shallots and garlic, and you need to stir the sprouts once or twice while they're in the oven to keep things from sticking. If caramel-colored breadcrumbs are not your thing, keep the heat low on the stove top when you add the sprouts and cover the pan with foil before you put it in the oven. It will still be delicious. —Merrill Stubbs
Heat the oven to 425° F. Trim and quarter the brussels sprouts (halve them if they're small). Tear the bread into rough crumbs about 1/3 inch in diameter; you'll need about 1/2 cup.
In an ovenproof pan that will work for serving, fry the pancetta over low heat until crisp. Add 1 tablespoon of the olive oil to the pan, and over medium low heat soften the shallot, 3 to 5 minutes. Add the garlic and whole thyme sprigs and cook for another minute. Turn the heat up to medium and add the croutons, stirring to coat them in the oil. Cook for a couple of minutes, until the croutons start to brown.
Push everything to the sides of the pan and turn up the heat to medium-high. Add another tablespoon of olive oil to the center of the pan, along with the sprouts. Cook for a minute or so, until they sizzle and start to brown. Stir everything together, adding salt and pepper to taste, and the nutmeg, and transfer the pan to the oven. Cook, stirring once or twice, until the sprouts are just tender, about 15 minutes, and everything is crisp and burnished.
Remove the thyme sprigs, shower the sprouts with the Parmesan (if using) and serve.