Mexico has somewhere between 500 and 2,000 kinds of pan dulce. The concha, named for its seashell crust of cracked sugar, is a 19th-century Mexican invention. Churros came from Spain and picked up a cajeta filling on the way. Pan dulce crossed the border with the families who made it, and panaderías were open in Austin and Los Angeles before 1900.
The donut shop is a different animal, American and early-morning, and for most of a century the two stayed in separate buildings. Then, in the late 2010s, Los Angeles put them together. Trejo's sold out its first morning in 2017. A year later a Downey shop called Donas went viral with mazapán and Selena-themed donuts and had lines at six in the morning.
What followed is a new kind of shop, run by Mexican-American, Salvadoran, Venezuelan and Mexican-Jewish families, where conchas sit next to glazed, the cold brew is horchata, and the best donut in the case might be half concha. One Seattle owner put the whole idea in a sentence.