Step 1

Peel the potatoes – if they are even in size, they can remain whole, or you could cut them into evenly sized pieces for quicker cooking (although bear in mind that the smaller the pieces, the more water gets into them, and you don’t want too watery a mash). Cover with cold water, add salt, bring to a boil, then reduce to a simmer and cook until they are tender.

Step 2

Meanwhile, if you are using cavolo nero or another kale, strip the leaves from the tougher stems and cut them into thick ribbons; if you are using spinach or chard, simply wash it. Warm a little olive oil in a hot pan, then add the greens and leave to wilt. Once they have collapsed, use a spoon to press down on the leaves, then tilt the pan and pour off any excess liquid. Use scissors to snip the greens up slightly.

Step 3

To make the bechamel, melt 60g of the butter in a pan, then add the flour and stir so it forms a thick roux. Whisk in the whole milk, then cook, stirring, until it thickens to a point when it coats the back of a spoon. Season with salt, pepper and nutmeg.

Step 4

Mix the greens with the bechamel, and add a tablespoon of grated parmesan.

Step 5

Once the potatoes are tender, drain them well and pass through a food mill or a ricer to mash them. Add the remaining 30g butter, the egg yolks and remaining parmesan, then season.

Step 6

Heat the oven to 180C (160C fan)/350F/gas Choose an ovenproof dish roughly 20cm x 20cm, grease with olive oil or butter, then dust heavily with breadcrumbs.

Step 7

Press half the mash into the base, pour in the greens and bechamel, then carefully cover with the rest of the mash. Dust the top with more breadcrumbs, then bake for 20 minutes, or until the top is golden and the edges bubbling.