1. Cook spaghetti according to pack instructions to boil.
2. Boil the cream with finely chopped garlic in a large saucepan. Let it simmer while stirring, until the cream hangs on to the fork, about 4 minutes.
3. Wash the mussels and make sure all the mussels are closed. Discard the questionable shells.
4. Add the mussels to the cream, turn up the heat and let them steam in the cream for about 3-4 minutes. When the shells open they are ready. Discard shells that do not open.
5. Cut spring onions into thin strips and pick leaves of basil.
6. Gently turn mussels, cream, spring onions and the basil together with the spaghetti, and serve.