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1
Preheat the oven to 110C/225F.
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2
Pour the milk into a saucepan and add the herbs and crushed garlic.
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3
On a medium heat, bring to the boil and leave to simmer for 5 minutes.
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4
Remove from the heat and leave to cool so that the milk infuses with the herbs and garlic.
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5
Once infused, strain to remove the herbs and pour the milk back into a large heavy-bottomed pan.
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6
Slice the potatoes as thinly as possible.
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7
Add them to the milk, separating them as much as possible, and place the pan on a medium heat.
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8
Bring the liquid to a simmer, stirring occasionally to stop them from sticking.
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9
After a few minutes, when the milk has thickened, add the cream and butter and gently agitate the pan so that everything is mixed inches.
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10
Add the salt, cayenne pepper and nutmeg.
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11
Be careful - cayenne pepper is strong stuff.
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12
This gratin will take more salt than expected, as the potatoes absorb quite a lot.
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13
Pour the potatoes into a baking dish at least 5cm/2 inches deep and measuring about 25 x 15cm/10 x 6 inches, trying to get them as flat as possible.
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14
The potatoes should be covered by about 1/2cm of liquid.
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15
A little less is fine, but if there is more liquid than that, do not add it.
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16
Tightly cover the dish with kitchen foil and bake in the oven for 4 hours.
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17
Every 45 minutes or so, gently press down on the potatoes with the back of a wooden spoon.
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18
Just before serving, flash the dish under a hot grill to gratinate it.
