As doughnuts go, there’s no outshining the pleasures of the cake kind.
Its crumb is among the most tender and moist of all sweet fritters, with satisfying, sink-your-teeth-in heft.
Biting into its craggy crust doubles down on the delight, especially when there’s icing or spiced sugar hugging the ring’s notches and crenulations, accentuating a cake doughnut’s singular exterior-interior contrast.
And yet—potatoes make cake doughnuts even better. To make them, you follow more or less the same formula as you’d use for a typical cake doughnut: Mix up a sweet, quick bread–like dough that’s lightened with chemical leavener(s); roll and cut it into rings and holes; and fry them in hot oil.
But with spuds in the mix, every element—from interior plushness to surface crunch—is leveled up.
And what’s really impressive is their shelf life: Potato doughnuts (which, by the way, don’t taste potato-y) retain those freshly fried qualities for hours if not days, so the payoff for making them yourself is especially sweet.
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Po-Tay-Dough
Adding potatoes (usually boiled and mashed) to bread doughs and sweets became a popular, thrifty response to food rationing during the first World War when wheat flour supplies dwindled.
But it’s endured because the spuds add moisture and starch that make the dough fluffier and more stale-resistant than your average cake doughnut.
America’s Sweet Relief—at Home and on the Front Lines
There are plenty of great reasons to make doughnuts with potatoes (see “The Dynamic Duo Behind the Fluffiest, Crispest Crumb”).
But when spud-based doughnuts became a widespread phenomenon in America during the early 1900s, it was mostly due to the war.
Federal food rationing during World War I made wheat flour scarce, so consumers were urged to eat inexpensive, widely available potatoes.
Government resources like the Economical War-Time Cook Book (1918) went so far as to recommend daily per-capita potato consumption—“2 to 3 medium-sized potatoes” for children and “6 to 8” for adults—which inspired cooks to work the spuds into breads and sweets.
As potatoes became an integral part of doughnuts, the treats became morale boosters on the front lines.
Salvation Army volunteers dubbed “Donut Lassies” made do with what was at hand, purportedly frying doughnuts in soldiers’ helmets filled with lard to serve as a comforting salve to homesick troops.
Their gesture became a revered contribution to the war effort, and the doughnuts a timeless symbol of Americana.
Floury russet potatoes are ideal: They’re naturally high in starch (20 to 22 percent by weight), which means they can bind up more added water than lower-starch varieties (16 to 18 percent).
That water-binding ability is key because it enables the cook to add a high proportion of liquid—which results in a fluffier, more tender, more shelf-stable doughnut—without making the dough unworkably soft and sticky, since some of the water is effectively “locked away” in the gelled starch.
After boiling and mashing the potatoes, we enriched them with butter, eggs, sugar, and most of a can’s worth of sweetened condensed milk.
The shelf-stable dairy is another nod to the doughnut’s wartime origins, and its high concentration of sugar and protein reinforces the potato doughnut’s lofty crumb and exceptionally crisp crust.
Plus, we had doughnut-glaze plans for the leftover sweet, syrupy milk.
We mixed the mash with flour, baking powder, and salt until it resembled thick cake batter and then chilled it for an hour or so to let it firm up.
Then we rolled the dough into a ½-inch-thick round, stamped out 15 rings and corresponding holes (a round of rerolling scraps was necessary but easy), and chilled the cut dough for another hour.
The Dynamic Duo Behind the Fluffiest, Crispest Crumb
The dough’s combination of potatoes and sweetened condensed milk makes for an exceptionally plush, crisp, and golden-brown doughnut with long-lasting freshness.
Here’s a breakdown of what they contribute.
Fluffiness: Both the potatoes and milk add water—but in a bound form: Potato starch absorbs water and gels when the spuds are boiled, and the high concentration of hygroscopic sugar and protein in the milk binds up its water molecules.
When that locked-away water is worked into the dough, it generates lots of steam during frying that expands the crumb, creating impressive loft.
Tenderness: The dispersed potato starch physically interferes with gluten formation, so the crumb is soft.
Delayed Staling: Baked goods stale when wheat starch crystallizes and traps water.
But potato starch impedes that: Its comparatively large granules block the wheat starch from crystallizing.
And unlike most starch, it’s covered in negatively charged compounds that repel one another like magnets, which deters the starch from packing together and allows water to remain in the interstices.
Rich Browning: Sweetened condensed milk, which is made by heating fresh milk to evaporate most of its water and then fortifying it with 40 to 45 percent sugar by weight, contains such a high concentration of protein and sugar that the dough browns quickly and deeply.
Crisp Crust: Because so much of the water is bound up, the dough is relatively dry and quickly forms a crust that limits oil absorption, so the doughnuts don’t taste greasy. The milk’s high concentration of sugar enhances this.
On the Fry
Meanwhile, we preheated a couple quarts of oil to 350 degrees—and we made sure to do it over relatively low and slow heat because the temperature of oil that’s heated gradually is much easier to regulate than oil that’s heated quickly.
The frying itself went fast: We added a third of the rings at a time to the pot, flipped them after about 90 seconds, and when they were uniformly golden brown, we transferred them to a bed of paper towels to drain. Same for the doughnut holes.
It was time to glaze. We whisked confectioners’ sugar, the leftover sweetened condensed milk, and a little salt with hot water, which ensured the mixture was smooth and runny—perfect for dunking the doughnuts and letting the excess drip off.
The crisp-crusted, remarkably plush result was equal parts nostalgia, resourcefulness, and brilliant science.
It doesn’t get sweeter than that.
Potato Doughnuts
Potato doughnuts, also known as “spudnuts,” are simply traditional doughnuts with a twist.
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