When Amirah Kassem was in the throes of opening her New York City bakery, Flour Shop, she took a break one afternoon to bake a cake for a friend’s son’s birthday. She’d made plenty of cakes for friends in the past, but this time was different: After she baked a full set of bright rainbow cake layers, she cut a hole in the center of each and filled the inside of the cake with multicolored sprinkles. She imagined an explosion of sprinkles when the cake was cut — like an edible version of all the piñatas she’d seen at parties while growing up in Mexico. “When the birthday boy sliced it open, it was a total paparazzi moment,” Amirah says. “Everybody pulled out their phone to take a picture.” Realizing she had a hit on her hands, she added the creation to the Flour Shop menu, and the cake exploded again — on Instagram. Famous fans like Beyoncé, Katie Holmes and Kelly Ripa shared photos of it, and Instagram called out rainbow and unicorn cakes as a top trend, using a Flour Shop cake as an example. Amirah shared the recipe (from her book, The Power of Sprinkles) so you can make one yourself!

Photographs by Henry Hargreaves