Baked Sweet Potatoes with Caramelized Onions and Shaved Parmesan
- 6 medium sweet potatoes (8 ounces each)
- 1 tablespoon unsalted butter
- 4 large yellow onions, cut in half, then into 1/2-inch-thick half-moons
- 3 tablespoons sugar
- 1 teaspoon coarse salt
- 1/4 teaspoon freshly ground pepper
- 2 tablespoons balsamic vinegar
- 1 1/2 ounces freshly shaved Parmesan cheese (about 1/2 cup)
Preheat oven to 450 degrees. Place potatoes on a baking sheet; bake until tender, about 45 minutes. Meanwhile, melt butter in a large nonstick skillet over medium-low heat. Add onions; cook until soft, about 15 minutes. Sprinkle with sugar, salt, and pepper; toss to coat. Continue to cook, stirring occasionally, until onions are very soft and caramelized, about 1 hour more, adding water a tablespoon at a time if pan dries. Stir in vinegar. Set aside; keep warm.
When the potatoes are tender, split open, and top with caramelized onions and shaved Parmesan. Serve warm.