Cook the pasta in salted water al dente.
Steam frozen broccoli in vegetable stock for 5 minutes. Set aside 1/4 of the broccoli florets and puree the rest.
Stir the hollondaise sauce and ground hazelnuts into the broccoli puree. Heat briefly and fold in the broccoli florets.
Season the sauce with salt, pepper and lemon juice and fold into the pasta. Finally sprinkle with chopped hazelnuts.