In the last decade a donut renaissance has swept across the United States. In the case of Boston (or, to be more specific, Somerville), bakers Heather Schmidt and Josh Danoff answered the call. The duo started Union Square Donuts in a small shared kitchen on the outskirts of its namesake neighborhood in 2013, selling their fluffy creations at local farmers’ markets. After slowly expanding—running a makeshift shop in the shared space and then selling donuts out of a tango dance school—a full brick-and mortar bakery and shop has finally opened in Union Square, along with a second location in Brookline and a stand in the Boston Public Market.

There’s an easy explanation for USD’s rapid ascent: the donuts themselves. They might look massive, but thanks to a tried-and-true dough recipe, they’re soft and airy. That perfect lightness lends itself to the sweet glazes and heavy-duty toppings that have become the maker’s signature.

A roster of original staples is always available, with glazed and frosted, yeast-based favorites like Sea-Salted Bourbon Caramel, Brown Butter Hazelnut Crunch, and Maple Bacon. But the shop also curates an ambitious selection of seasonal creations; Strawberry signifies springtime, Creamsicle comes with summer, and yes, Pumpkin Spice hits shelves in fall. You’ll always find a few cake-based doughnuts in the mix, like Old Fashioned and Birthday Cake, as well as donut holes and more substantially sized “doughies.” Most recently, USD took an adventurous dive into savory breakfast territory with the release of its breakfast sandwiches; an Egg and Cheese and a Smoked Salmon rendition are each stuffed between baked doughnut dough. (Pro tip: Ask for a sprinkle of everything spice.)

The Union Square location serves as baking headquarters, so it’s no surprise that the kitchen takes up far more square footage than the seating. But there are still a few tables for us to linger with a donut and a draft cold brew amidst exposed brick and rough-hewn wood. It’s the perfect place to gaze into the open baking area, looking for hints and contemplating the many mysteries of what makes these airy pastries so good.