First, make the caramelised shallots. Melt the butter in a saucepan over a medium heat. Add the s iced shallots, garlic and pinch of salt and allow to fry for 3 - 4 minutes until the shallot begins to soften.
Sprinkle in the sugar and pour in the vinegar along with 50ml water. Stir together the ingredients and allow to gently simmer and reduce for approximately 5 - 6minutes until jammy and glossy. Set aside.
Next, melt the butter for the mussels in a large pan with lid. Add the shallots, garlic and a small pinch of salt and gently fry for 3 - 4 minutes. Finely chop the stalks of the parsley and put in the pan and roughly chop the leaves reserving them for later.
Add the mussels to the pan before pouring in the white wine. Bring the pan to a gentle simmer before placing on the lid to steam for 3 - 4 minutes.
In the meantime, make the toasts. Heat the grill to high before toasting one side of the bread. Turn the bread over and spread the prepared caramelised shallots on top of the un-toasted side. Sprinkle over the grated cheese and return to the hot grill until the cheese is melted and bubbling - approximately 1 - 2 minutes.
After the mussels have steamed and the shells have opened, pour in the cream and add half the parsley leaves. Season with cracked black pepper and stir well.
Pour the mussels into a large sharing bowl or simply serve the pan straight to the table. Sprinkle with the remaining chopped parsley and serve alongside the toasts for dipping