Heat oven to 160C/140C fan/gas 3.
Brush the oil over the bottom and sides
of a 25 x 19 x 5cm ovenproof dish. Put
the milk, garlic, 4 thyme sprigs, bay
leaf and shallot into a saucepan. Bring
just to the boil, then remove from the
heat and add the nutmeg and a little
pepper. Set aside to infuse.
Peel then slice the potatoes very thinly.
Pat them dry. Layer half the slices in the
dish, overlapping slightly, then season.
Strain the infused milk into a jug. Put
the crème fraîche into a bowl, then
gradually pour in the milk, whisking until
smooth. Add the stock and thyme leaves.
Return this liquid to the jug, then pour
half of it over the potatoes in the dish.
Layer up the rest of the potatoes, then
add remaining liquid, the cheese and a
grind of pepper. Sit the dish on a baking
sheet and bake for 1¼-1½ hrs until golden
and tender – test by inserting a sharp
knife through the potatoes. Stand for 5 mins
before serving, sprinkled with thyme sprigs.