Preheat your oven to 350 degrees.
Peel and halve the red onion.
Wash the potatoes, leaving their skins on and slice thin in a food processor or mandolin along with onion.
Tip into a large sturdy roasting tray and season.
Grate 1/4 of the nutmeg on top, crush in 2 cloves of garlic and pour in 225 ml of cream.
Tear in the anchovies and add large handful of finely grated Parmesan.
Add the bay leaves, pick the leaves from a few thyme sprigs and add a good drizzle of olive oil.
Use your clean hands to quickly mix and toss everything together, then put the tray over medium heat.
Pour in 200 ml of water, cover tightly with tin foil and leave on heat.
Give the tray a shake so nothing sticks.
Remove the tin foil and finely grate over another layer of Parmesan.
Drizzle the remaining thyme sprigs with oil, scatter on top and put in the oven on the top shelf to cook for 15 minutes or until golden brown and bubbling.