Most nights, before my partner and I head off for bed, someone (I won’t say who) has to remember to soak the oats. It is a task of utmost necessity, seemingly more important than taking the dog out or locking the front door. If someone forgets until climbing under the covers, the other is sorry. But not too sorry – it has to be done, or else we’ll be stuck with oatmeal for breakfast.

For years now, muesli, the Swiss cereal traditionally made with rolled oats, nuts and grated apple, has been our chief breakfast staple. We are smitten with the classic method that soaks the oats overnight first, turning them tender, springy and the slightest bit sweet; we are also a little addicted to how nourished muesli makes us feel. We pick up requisite ingredients when we travel, passing up boxed mixes for the bulk bins, and consider any imposition a success when we make converts of our hosts.

If there is a trace of fanaticism here, it would suit: The original muesli was an early 1900s sanitarium staple, created by Swiss physician Maximilian Bircher-Benner, who thought the solar energy in raw fruits and vegetables was the key to his patients’ health. Muesli, which initially went by the less-dear “apfeldiatspeise,” or “apple dietary dish,” consisting of little more than grated apple, was Bircher-Benner’s formulaic approach to that philosophy, something he could apply to a clinical setting in a regimented way.

At his Vital Force health clinic in Zurich, Bircher-Benner served the “little mush” to his patients three times a day as a starter course for each breakfast, lunch and dinner, eventually becoming so linked with the practice that “Birchermuesli” gained a fan base beyond his own setting.

THE ORIGINAL RECIPE called for 2 small apples with skin, 1 tablespoon of oats soaked in 3 tablespoons of water, and 1 tablespoon each of lemon juice, ground hazelnuts and sweetened condensed milk – the last an addition that played to food-safety concerns of the day that cow’s milk was unsafe.

Muesli now rarely appears in its original form, the proportion of oats to fruit having shifted to suit the need for a full meal; the condensed milk, water and lemon most often replaced with milk or juice; the apple sometimes completely forgone.

Commercial boxed versions offer toasted muesli, muesli tumbled with dried fruits and nuts, and oiled, sugared and baked muesli – the granola counterpart with a more successful “healthy” marketing campaign.

Few Swiss, at least those I’ve spoken to about muesli, will claim there is one correct way to serve it. Many prefer the traditional approach. Take Christian Haudenschild, who served in the Swiss military with Bircher-Benner’s son. He soaks the oats briefly, for 30 minutes or so, in milk before adding chopped apple. At the Swiss Bakery in Springfield, Va., Laurie and Reto Weber offer muesli every day on their cafe menu, soaking the oats overnight in milk, then adding grated apple, yogurt, hazelnuts and honey, an iteration as close to the Bircher-Benner original as they come.

In any case, the potential for variation can been seen as part of muesli’s appeal. “Essentially anything fresh and available goes in there, so, unlike packed mixes with dried fruit, it is different every time,” said Haudenschild. “You still can use a mix as a basis and then supply the fresh fruit, but check the ingredients for too much sugar.”

MY OWN PREFERENCE has been for a version bearing more of the qualities of the Bircher-Benner original, tweaked to suit contemporary tastes.

Over the past few years, I have tried soaking the oats in milk; in orange juice and in lemon juice diluted with water (classic); in cranberry juice (much too tart); in oat milk (earthy); and in kombucha (the best of the bunch). Once, on a tip from a Swiss farmer who grows vegetables in Maryland, I whirred up a banana-coconut milk for soaking, which was a delicious choice if a rib-sticking one. I’ve used barley and rye flakes in addition to the oats; mace, nutmeg and cardamom for the spicing.

I also have used freshly rolled oats using local grain and a countertop mill, which produced such complex, nuanced results, it’s a shame that the local oats are so hard to find.

Ultimately, the take I found the most compelling for everyday mornings was one of the most straightforward and the most seasonal: thick-cut rolled oats soaked overnight in unsweetened apple cider – just enough to plump and tenderize them while leaving them separate and light – combined with plenty of coarsely grated apple, raisins, nuts and seeds.

The mix is light yet substantial, its ingredients and flavors clinging together and producing a simple dish of unexpected depth.

As with all minimalist concoctions, the quality of ingredients is crucial here: The better the apples and the fresher the cider, the better the muesli. In warmer months, perhaps swap the cider for kombucha and the apple for juicy, acidic berries and stone fruits. For muesli, the best guidance is simple: Look around and see what’s fresh.

APPLE CIDER MUESLI

Here, oats are transformed by an overnight soak in a small amount of liquid, which renders them tender and chewy but not porridgelike.

For the apple called for here, avoid varieties like Red or Golden Delicious, or McIntosh; their flesh is too watery and will dilute the flavor of the muesli.

Take the nuts, seeds and raisins called for here as suggestions; if you prefer almonds, golden raisins and sunflower seeds, use those instead. Tiny hemp seeds are a nice addition, as well.

If you are making more than a single serving, build each portion in a separate bowl.

1 serving (makes 1¼ cups)

½ cup thick-cut rolled/old-fashioned oats (do not use instant or quick-cooking oats)

¼ cup plus 1 tablespoon unsweetened apple cider (may substitute unflavored kombucha)

1 to 2 tablespoons raw walnuts, broken into pieces if whole

1 tablespoon raw, hulled, unsalted pumpkin seeds (pepitas)

1 to 2 tablespoons raisins

½ medium apple, cored, preferably a fine-grained, crisp variety such as Golden Russet (may substitute a crisp, slightly tart variety such as Pink Lady)

Pinch ground mace (may substitute ground cinnamon or cardamom, or freshly grated nutmeg)

⅓ cup plain yogurt, for serving (optional)

Place the oats in a serving bowl. Pour the cider over the oats; use your fingers to pat the oats down so the surface is moistened.

Cover with a plate to rest overnight at room temperature.

In the morning, use a spoon to fluff and separate the oats; they should be springy yet slightly tacky. Add the pumpkin seeds, then the walnuts and raisins (to taste).

Use the large-holed side of a box grater to grate the apple down to the peel, discarding the peel (or reserving it for another use).

Quickly stir the grated apple into the oats (to keep the fruit from browning).

Sprinkle with the mace. Spoon the yogurt on top, if using, just before serving.