Begin by lightly sautéing chopped shallot and parsley in butter (or butter mixed with some olive oil), sprinkle this soffritto with a bit of cayenne pepper (not too much, just enough to give the dish a little 'kick') then pour over a cup or so of white wine. Allow to simmer for a few minutes.
Add your mussels, in their shells. Cover and allow the mussels to steam until they open, then transfer the mussels with a slotted spoon to a heated serving vessel (I find that an enameled cast-iron soup pot is ideal) and keep warm while you make the sauce.
Allow the juices in the pot to reduce for a minute or two over high heat, then add a good pour heavy cream and sweet curry powder (or curry paste if you have it) to taste. Allow to reduce to a saucy consistency and pour over the mussels.
Sprinkle with a bit more chopped parsley and serve immediately.