Preheat the oven to 200°C/Fan 180°C/Gas 6. Give the potatoes a wash and then chop into small wedges, place in a shallow roasting tray and drizzle with oil, salt and pepper. Roast for 30-35 minutes.
Meanwhile in a large pan, add the butter and stir fry the shallots for 2-3 minutes, then add the parsley and white wine and simmer.
Once the mixture has reduced add the cream, stock, lemon juice and garlic puree and bring back to the boil. Then add the mussels and cook for 5 minutes or until they have opened. Remove any that have not opened. Season the sauce and serve, with wedges of lemon.