Chop the basil, onion and garlic. Cook the pasta al dente according to the instructions.
Fry the garlic and onion in the oil, add the cream and crème fraîche, bring to the boil briefly. Stir in the basil and season the sauce with salt, pepper and lemon juice.
Drain the pasta. Mix the egg yolks with 2 tablespoons of the sauce, stir into the entire sauce and serve immediately with the pasta. Serve with freshly grated parmesan.