Portland's doughnut scene abhors a vacuum.

When Blue Star Donuts declared bankruptcy and began closing locations, Fills Donuts announced plans to rise in what was once the only Blue Star, on the same stretch of Northwest Washington Street as Grassa and Lardo. Like those spots, it's part of Kurt Huffman's ChefStable restaurant group, as is Bar King in Southeast. The Bakery at Bar King's Katherine Benvenuti is also the main pastry brain at Fills, in tandem with Noble Rot pioneer and "cannabis chef" Leather Storrs, who's also one of Huffman's oldest friends.

"Kurt and I have been talking about doughnuts for years," says Storrs. "Kind of humorously. And kind of seriously."

Fills embraces the Berliner as its chosen style of doughnut. Though to some extent, a filled doughnut is a filled doughnut, whether it's a Bavarian Kreme at Dunkin', an Italian bomboloni, or a Polish paczki, Berliners are the German version, though in Berlin itself, they're known as Pfannkuchen. At Fills, the focus is on seasonality, quality ingredients, and unexpected flavor combinations, both sweet and savory.

Generally speaking, Storrs does the savory and Benvenuti the sweet, though there's a constant exchange of ideas.

"I think, for Leather and I, if we were going to do doughnuts, it needed to be inspiring," says Benvenuti. "We're basically using the doughnut as the boundary for whatever we want creatively."

What also sets Fills apart is its levain-based dough, which is mixed daily starting around 3 am, since it needs four hours of proofing.

"With levain versus sourdough starter, you're not oversouring it," says Benvenuti. "So you get all of those lovely sweet notes."

But not too sweet, which is what brought Storrs into the fold.

"I don't love doughnuts personally, probably because I find them to be toothachingly sweet," he says. "But Katherine's dough has this marvelous, very gentle sweetness, a super tang from the levain, and an airiness that's kind of hard to describe."

Fills' opening menu includes such flavors as white chocolate passionfruit, masala chai, chocolate hazelnut, and a fairly traditional Boston creme. Storrs' first special was a chicken liver mousse donut with grape mostarda glaze and fried onions—elements of a dish you certainly would have ordered without hesitation along with a bottle of gamay noir at Noble Rot. This week, you'll find a manchego cream doughnut topped with Marcona almonds, more manchego and what Benvenuti calls quince pâte de fruit ($4.50), but which Fills' Instagram identified as—pun alert—"quince leather."

Here are the details on four Fills donuts from the usual menu:

Cinnamon Apple ($3.25)

Despite the most traditional Berliner being, essentially, a jelly doughnut, Benvenuti plans to use only seasonal fruit, even when it's cooked. Her apple butter filling—made from Kiyokawa Family Orchards Mountain Rose apples—has the freshness of homemade applesauce. It's topped with a cinnamon buttermilk glaze.

"I really want people to get used to things leaving and coming back," Benvenuti says. "So, goodbye apricots, hello apples. Goodbye apples, hello Meyer lemons. That flow that's pretty natural to chefs can be so easily represented in the doughnut shop."

Pimento Cheese ($3)

Call it a lunch doughnut. Or a kolache-doughnut hybrid. When Storrs suggested this one, Benvenuti responded: "That's ridiculous! I'm totally into it."

On first bite, you might expect this doughnut's blob of orange cream to have a little sweetness, à la red bean paste. But nope, it's a straight-up spicy-savory blend of cheddar, cream cheese, roasted peppers, Mama Lil's Peppers, cayenne, mayonnaise, mustard and salt, topped with hot honey glaze and more than a few pinches of toasted sesame seeds.

Breakfast Sandwich ($6)

Is a doughnut a sandwich? It is if you've got unfilled, day-old doughnuts. "Honestly, the time that they sit overnight is one of the ingredients," says Storrs. "The dough has a bit more tooth to it." The doughnuts, which are probably less sweet than Hawaiian rolls, are cut in half, griddled in butter and filled with a "quick scramble" of bacon and eggs, plus a chile aioli. You can also add cheese for an extra 50 cents. "The pro move is pimento cheese," says Storrs.

Maple Bacon Butterscotch ($4)

Yeah, they went there.

"We didn't want it to be just a maple bacon doughnut," says Benvenuti. "And using bacon in general, it was hard to do without feeling, um…"

"Derivative," Storrs says.

One of Benvenuti's inspirations for Fills' version of the Voodoo Doughnut stalwart was a dish called "bacon, butterscotch, apple, thyme" from the Chicago restaurant Alinea. It's also basically a butterscotch budino doughnut. The earthy and sophisticated custard begins with handmade caramel and is finished with single malt scotch. The doughnut also gets a propane torch at pickup, to "wake up" and crisp the bacon.

"Is it an homage, a nod?" asks Storrs. "It is. But it's also a flex. Like, 'Look what we did with your crappy maple bacon doughnut.'"

Fills Donuts, 1237 SW Washington St., 503-477-5994, fillsdonuts.com. 8 am-2 pm Wednesday-Sunday.