Wash the mussels thoroughly and put in a large saucepan with the garlic and cider. Bring to the boil, cover and cook over a medium heat for 4–5 minutes until all the shells have opened. Discard any that remain closed after cooking.
Strain the mussels through a colander and put in a large bowl, cover with foil and place in a very low oven to keep warm.
Pass the cooking juices through a fine sieve into a clean saucepan and bring to the boil. Whisk in the cream and simmer for 3–4 minutes, or until thickened slightly. Season to taste with salt and pepper.
Pour the sauce over the mussels, scatter over the parsley and serve immediately with plenty of crusty French bread to mop up the juices.