It’s simple enough—make mashed potatoes, sprinkle with bacon and cheese, top with yolks—but this central Swiss dish is comfort food at its finest.

According to Marianne Kaltenbach, there are variations on the theme in cantons Obwalden and Zug, as well as the Nidwaldner Ofetori, which omits the yolks.

The name, Ofenguck means “oven look” in Swiss German, perhaps referring to the bright orange yolks peeking out at you from the oven.

Aside from Kaltenbach, there are many recipes to be found online from sources like Betty Bossi and swissmilk (though theirs is rather unorthodox, omitting the yolks on top and using boxed mashed potato flakes).

Some, like Annemarie Wildeisen and Fooby, add some veg to their versions—Brussels sprouts and leeks respectively—but I prefer a salad on the side.

This is easily made vegetarian friendly, just omit the bacon in favour of a bit more cheese.

1 kg potatoes, peeled and cubed

150 ml milk

1 tbsp butter

nutmeg, salt and pepper

4 eggs, separated

200 g bacon, chopped

100 g Sbrinz, grated

Preheat oven to 180 C / 400 F / gas mark 6.

Put the potatoes in a large pot and cover with water, adding a pinch of salt. Bring to a boil over high heat and let cook for about 20 minutes, or until the potatoes are soft and slide off a paring knife when pricked (the time will vary based on the variety of potato).

Once they are cooked, drain the potatoes. Now either add them back to the pan and mash them with a potato masher, or put them through a passe vite, and add the milk, butter, nutmeg, salt and pepper. Put aside and let cool slightly.

Using a large bowl and an electric mixer, whip the egg whites until stiff.

Gently fold the egg whites into the potato mixture, then spread into a large casserole dish.

Sprinkle with the cheese and bacon.

Wet the back of your spoon and make four indents into the potatoes. Slide an egg yolk into each.

Bake for about 20 minutes, or until the cheese is melted and the bacon has crisped up.

• It's best to use potatoes that are suited for mashed potatoes (like Russet or Yukon Gold: you want a floury/starchy potato, not waxy). Their name in German is mehlige (not festkochend) and they are usually listed as so in the grocery store.

• If your mashed potatoes look a bit dry, add a bit more milk.

• If you don’t have Sbrinz another hard cheese, like Parmesan, will do.

• Serves four.