This is a savory alternative to the sweet potato confection often served at the holiday table. Shallots, thyme, fennel seed and mustard balance the natural sugars in the sweet potatoes, and a cheese and breadcrumb topping add crisp texture. We couldn’t resist finishing the casserole with a drizzle of honey or sorghum syrup to pull it all together. If you own a mandoline, it makes quick work of slicing the shallots and sweet potatoes. Use the small holes on a box grater to shred the cheese; fine shreds better integrate with the breadcrumbs than coarse shreds. You can prepare the recipe through the baking, then let cool, cover and refrigerate for up to two days. To finish, allow the casserole to stand at room temperature while the oven heats to 425°F, then make the cheese-breadcrumb mixture, top and bake as directed.