Preheat the oven to 200C/180C fan/gas mark 6.

Bake the potatoes in their jackets for about 1 hour until tender in the center.

Make the white sauce by melting the butter in a saucepan.

Stir in the flour and cook for 1 minute.

Gradually whisk in the milk.

Once all the milk is added, keep stirring and bring everything to the boil.

Simmer for 1 minute.

Remove from the heat and stir in the cheese and parsley, then season with salt and pepper.

Cover the surface with cling film to prevent a skin from forming.

When the potatoes are cooked, cut in half then scoop out the centers and roughly mash.

Set the skins to one side on a baking tray.

Add 1/2 of the white sauce to the mashed potato and mix.

Spoon the potato mix back into the potato skins.

Cover the top of each potato with a strip of sole, season, then place back in the oven for 10 minutes or until the fish is cooked.

Mix together the remaining white sauce and prawns and loosen if necessary with a little more milk.

Remove the potatoes from the oven.

Pour over a little of the prawn sauce and scatter with the remaining parsley.