How to Make It
In a saucepan, heat the oil. Add the pancetta and cook over moderate heat until browned and most of the fat has been rendered, 4 minutes. Add the onion and rosemary, cover and cook over moderately low heat, stirring occasionally, until the onion is tender and golden, 10 minutes. Stir in the marmalade; season with salt and pepper.
Bring a large saucepan of salted water to a boil. Add the pasta and cook until al dente. Drain the pasta, reserving 1/3 cup of the cooking water.
Return the pasta to the saucepan. Add the onion-orange mixture and the reserved cooking water; toss well. Season with salt and pepper and transfer to plates. Sprinkle with the cheese and serve right away.