The Cronut croissant-doughnut hybrid was the food phenomenon of 2013. There were long lines at the bakery where Cronuts were invented, and they were going for hundreds of dollars on the black market.

The 1990s were a golden era for donuts, when chains and local bakeries alike weren’t afraid to experiment with bold flavors, neon colors, and over-the-top toppings. Mall food courts, gas stations, and ...