Mushroom and Hazelnut Terrine

Finely chop the chestnut mushrooms, shiitake mushrooms, and rehydrated porcini. Dice the shallots, mince the garlic, strip the thyme, chop the parsley, and grate the Gruyère. Lightly beat the eggs. Line a 900 g loaf tin with two overlapping sheets of baking parchment, leaving an overhang.

Spread the hazelnuts on a dry baking tray and toast in an oven preheated to 180°C (160°C fan) for 10–12 minutes, until the skins are splitting and the nuts smell deeply nutty.

Tip the hot hazelnuts onto a clean tea towel, fold over and rub vigorously to remove most of the skins. Set aside whole — do not chop.

Return the oven to 170°C (150°C fan). Place a large wide pan over high heat and add the olive oil. Add the chestnut and shiitake mushrooms in a single layer and cook for 8–10 minutes without stirring, until deeply golden and all liquid has evaporated.

Reduce the heat to medium, push the mushrooms to one side, and add the butter, shallots, and garlic. Cook for 3–4 minutes, stirring, until the shallots are translucent and softened.

Add the chopped porcini and pour in the sherry and 4 tablespoons of the reserved soaking liquid. Cook for 4–5 minutes, stirring frequently, until the liquid has fully evaporated and the mixture is dry and paste-like.

Stir in the thyme, nutmeg, salt, and pepper. Spread the mixture onto a baking sheet and leave to cool until barely warm, about 15 minutes — do not add the eggs while it is hot.

Transfer the cooled mushroom mixture to a large bowl. Add the eggs, breadcrumbs, Gruyère, and parsley. Fold together until combined, then gently fold in the whole hazelnuts, distributing them evenly.

Pack the mixture firmly into the prepared tin, pressing it into the corners with the back of a spoon. Fold the parchment overhang over the top and press down.

Place the loaf tin in a deep roasting tray and pour in enough boiling water to come halfway up the sides. Bake at 170°C for about 48 minutes, until the terrine is set, has pulled slightly from the sides, and a skewer inserted into the centre comes out clean and hot.

Remove the tin from the bain-marie and leave to cool to room temperature. Once cool, weight it down with a second loaf tin or a board topped with two 400 g cans. Refrigerate weighted for at least 8 hours, or overnight.

To unmould, lift out using the parchment overhang, peel away the paper, and slice with a sharp knife wiped clean between each cut. Finish with a pinch of flaky sea salt on each slice. Refrigerated and tightly wrapped, the terrine keeps for up to 4 days.