Peel the garlic and scrub the potatoes.
Bring a large saucepan of water to the boil and add the salt.
Add the garlic and potatoes and simmer for 10-15 minutes until they are cooked.
Drain the potatoes and place in a clean tea towel. Retain the garlic.
Remove the skins with a blunt knife or use the tea towel.
Grate the Lancashire cheese and cut the mozzarella into pieces.
Put the potatoes in the bowl of a food processor.
Process the potatoes for 1 minute until totally smooth.
Return the mixture to the saucepan.
Finely chop or crush the garlic and add to the potatoes with the cheese, creme fraiche, milk and pepper.
Over a medium heat, stir the mixture until the cheese melts.
Beat vigorously for about 3 minutes.
The mixture should start to come away from the sides and be stretchy and elastic when it's ready.
Check the seasoning before serving and grate in some nutmeg if liked.