Bring a large, heavy based saucepan of lightly salted water to the boil. Add the pasta and cook until tender but still a little firm.
Combine the saffron infusion (as per packet instructions), sour cream, ham and grated pecorino cheese in a separate large, heavy based saucepan. Heat to a simmer and cook for 5 minutes, stirring constantly. Season with salt and pepper.
Remove the saucepan from the heat and stir in the egg yolks.
Drain the pasta and add to the saffron sauce. Toss well and serve immediately.