Preheat the oven to 200C.

Gather the chestnuts and make a horizontal cut across the top of the whole nut, and one cut on each side, providing a larger surface area for the skin to split open and make it easier to peel the nuts. Try not to cut the nut itself (though it’s not the end of the world if you do).

Arrange the nuts on a baking tray in a single layer, cut side up, and roast for 30-35 minutes. You’ll know they’re ready when they’re golden brown and tender, and the skin has pulled away from the cuts you made.

Remove the chestnuts from the oven, wrap them up in a towel and set aside for 5-10 minutes to steam and cool.

When cool enough to handle – but still quite hot – peel the chestnuts of both the outer and inner skin layers. The cooler chestnuts get, the harder they are to peel. If you like, reserve a few chestnuts pieces to crumble over the top of the pasta.

Roughly break up the nuts into smaller pieces and put them in a bowl of a food processor or immersion blender chopping bowl. Add the garlic cloves and grana Padano and blitz until the chestnuts are a breadcrumb consistency.

Add the sage and oregano, lemon juice and salt, and a quarter or so of the oil and pulse again. Little by little, add oil and pulse until it becomes a pesto consistency – less oil for a thicker, chunkier pesto for dips and sauces, more oil for a smoother, thinner pesto for pasta sauces, vinaigrettes and spreads.

Set the pesto aside if making the pasta the same day or store in the fridge for 2-3 days.

To make the Sage and Chestnut Pesto Linguine, start by heating the oil in a large frying pan or chef pan with high sides. Sauté the Brussels sprouts over medium heat, cut side down, until they start to turn golden brown, around 5-7 minutes. Stir and continue to cook for another 2-3 minutes, stirring frequently, until tender.

Meanwhile, cook the pasta as per the packet directions and drain, making sure to reserve a cup of the pasta cooking water.

When ready to serve, remove everything off the heat (pesto turns black if things are too hot). Add the drained pasta to the frying pan with the Brussels sprouts, add 2-3 tablespoons of pesto on top and ¼ of the reserved pasta cooking water. Gently mix until the pesto becomes and emulsified sauce, adding more pesto and pasta cooking water as needed.

Scatter the reserved chestnuts over the top (if you kept them), add extra cheese and serve.