This was utterly yummy, comfort food at its very best!
Serves 6 as a side or 4 as a main course.
6 garlic cloves
1 onion, halved
3 bay leaves
3 thyme sprigs, plus a sprinkle of leaves
600ml pot double cream
600ml whole milk
140g diced pancetta
25g butter, plus a knob
400g wild mushrooms, roughly chopped after cleaning
1¼kg medium potatoes (I used Maris Piper)
1 whole nutmeg
green salad, to serve
Put the garlic cloves, onion, bay leaves, thyme, double cream and milk in a pan. Bring slowly to the boil over a low heat, partially cover with a lid and cook for 20-30 mins until the onion is tender and the cream mixture slightly thickened. Turn off and leave everything to infuse for 1 hr.
Strain the cream mixture into a jug (or bowl) and discard the herbs. Put the garlic cloves and onion in a food processor or blender and whizz until smooth – add a drop of the cream if it helps. Stir the paste back into the rest of the cream and season with 2 tsp salt.
Put the pancetta in a cold frying pan and cook gently, over a low-medium heat so the fat melts into the pan, until the pancetta is really crispy. Lift out with a slotted spoon, add the butter and mushrooms and turn up the heat, frying the mushrooms, until golden and dry.
Leave the skins on the potatoes and slice as thinly as possible. Grease a large baking dish with a little more butter. Layer up the potato slices, scattering over some of the cooked pancetta, the mushrooms and a little freshly grated nutmeg and pepper as you go. Finish by slowly pouring over the cream so that it settles among all the layers, then scatter over a few more thyme leaves. Cover with foil.
Heat oven to 180C/160C fan/gas 4. Bake the gratin for 1 hr, then remove the foil and bake for 35-45 mins more until golden and crispy on top. Poke a knife in to check the potatoes are tender, then leave for 10-15 mins to settle, before serving with a salad, if you like.