Toss sprouts with 1 tablespoon oil; arrange cut side down on a baking sheet.
Sprinkle with salt, pepper, and pancetta. Roast 1820 minutes or until sprouts are tender.
Meanwhile, cook pasta according to package directions.
Drain, reserving 1/4 cup cooking water. Return pasta to pot.
Add garlic to sprouts; toss well.
Add sprouts, Parmesan, thyme, and a few tablespoons reserved pasta water to pasta; stir in remaining 2 teaspoons oil. Spoon into 4 bowls; sprinkle with hazelnuts.