Heat the oven to 450 F.

Poke the potatoes a few times with a fork and then place them on a parchment lined baking sheet. Bake the potatoes for 1 hour, until soft all the way through, then cut them in half lengthways and scoop out the flesh into a medium bowl. Set aside the skins (you’ll be using these later). Add the butter, the cream, gorgonzola, ½ teaspoon of salt and a good grind of pepper to the potato flesh and mash to combine.

Put the four reserved half-potato skins on a baking sheet, and divide the remaining ½ tablespoon of butter between them and sprinkle over a generous pinch of salt.

Bake for 8 minutes more, until they crisp up, then remove from the oven.

Bring a medium saucepan half-filled with salted water to a boil, then blanch the spinach for 10-15 seconds, until wilted. Drain, refresh and drain again, squeezing out as much water as you can, then stir into the mash mix until well combined. Pile the spinachy mash into the empty potato skins, then return them to the oven for 15 minutes more, until the top of the mash is crisp and browned.

Melt the remaining butter in a small frying pan on a high heat for one to two minutes, until it starts to brown, then fry the broken walnuts for 30 seconds, stirring constantly to stop them catching and burning. Spoon the nuts and melted butter from the pan over the potatoes and serve hot.