Preheat the oven to 180C/gas
4/fan 160C and butter a shallow
ovenproof dish. Layer the potatoes,
then the parsnip in the bottom of
the dish with two of the sliced garlic
cloves and sprinkle over a little salt
and half the rosemary. It’s best to
keep the potatoes buried under the
other vegetables because they go
black if they are on top of the gratin.
Pour the cream and milk into a
large saucepan, add the rest of the
rosemary and garlic, the carrots
and a little seasoning. Bring to the
boil, then turn the heat to the lowest
it will go and simmer for 3 minutes.
Pour the carrots and cream over
the other vegetables, and spread
the carrots out. Sprinkle over the
parmesan, cover with foil and bake
for 40 minutes. Remove the foil and
bake a further 20 minutes until
golden and bubbly.