1. Cook the fettuccine in a large pot of boiling salted water until al dente (firm, yet tender). Drain
2. In a large skillet, melt the butter, add the cream and sprig of rosemary, and bring to a boil.
3. In a large bowl, beat the egg yolks and pour in the cream mixture, a little at a time, whisking constantly. Remove the rosemary. Add the fettuccine and toss well, coating it completely. Return everything to the skillet and cook over medium heat, stirring constantly, to warm the pasta. Season with salt and pepper and parmesan cheese. Serve hot.