Cook the spaghetti in a pan of lightly salted boiling water for 8–10 minutes, or according to the packet instructions, until al dente.
Meanwhile, heat the oil in a frying pan, add the garlic and spring onions and cook for 2 minutes. Tip the defrosted shellfish in a sieve, rinse with cold water, drain well, then add to the pan. Fry for 3–4 minutes until the prawns are pink and scallops just cooked.
Lift the shellfish out of the pan with a slotted spoon and reserve. Add the wine and cream to the pan and increase the heat to reduce the sauce.
Return the shellfish to the sauce, stir well and simmer for 2 minutes. Add the parsley and spaghetti, season and mix well, using 2 spoons to combine the spaghetti with the sauce. Serve with Parmesan.