Scrub 750g of mussels then check them carefully for cracked shells. Discard any that refuse to close when tapped firmly. Put them in a deep saucepan over a high heat and pour in 100ml of white wine or vermouth. You can use water at a push.
Bring to the boil, covered tightly with a lid, and let them cook for 2 or 3 minutes until their shells have opened. Remove from the heat and pull the mussels from their shells. Reserve the cooking liquor.
Wash 250g of dark green cabbage leaves, then roll them up and shred into pappardelle-thick ribbons. Melt 35g of butter in a shallow pan over a moderate heat and add 1 tbsp of olive oil. Peel and thinly slice 2 cloves of garlic and add to the pan, letting them cook for a couple of minutes.
Flatten 6 juniper berries and add to the butter, then add the shredded cabbage. Fry for a couple of minutes until the cabbage is bright green and starting to soften. Cover with a lid and continue cooking for 3 minutes.
Remove the cabbage and set side. Pour in the reserved cooking liquor and bring to the boil, then add 6 tbsp of double cream and a little pepper and shake back and forth until you have creamy sauce. Return the cabbage and mussels briefly to the pan, then serve. Enough for 2
Lay the cabbage leaves on top of one another then, as you pour the cream into the stock, gently shake the pan and give it the occasional swirl to bring the two together to form a thin, impromptu sauce.
There is already some dark, black-green cavolo nero about. Its slight bitterness is so good with the sweet mussels.