Flour Shop founder shares the secrets to the SoHo bakery’s Rainbow Explosion cake

"The Power of Sprinkles" shares how to make Flour Shop's Rainbow Explosion cake.
"The Power of Sprinkles" shares how to make Flour Shop’s Rainbow Explosion cake. Photo Credit: Lady V Second Time Around

At Flour Shop, it’s all about the sprinkles.

“We have an entire sprinkle closet and we mix hundreds of pounds a day,” says Amirah Kassem, founder of the SoHo bakery. “I think we go through over 3,000 pounds of sprinkles a year, probably more.”

In her new cookbook, “The Power of Sprinkles,” out Tuesday, Kassem shares how to make the bakery’s signature Rainbow Explosion cake, from the colorful layers to the cascade of sprinkles once it’s sliced.

“We had so many different people posting and tagging us on Instagram their versions they made at home, and struggles they had and questions about it,” Kassem says. “I wanted to encourage people to do it because I know some baking books can be intimidating, everyone thinks it’s hard. But I really believe that you could start at whatever level you’re at. You can start with a cake mix if you wanted, or you can get really crazy and start doing some of the custom stuff.”

Since it all comes down to the sprinkles, we asked Kassem to share her tips:

Amirah Kassem, founder of Flour Shop, from her new cookbook "The Power of Sprinkles."
Amirah Kassem, founder of Flour Shop, from her new cookbook "The Power of Sprinkles." Photo Credit: Henry Hargreaves

The signature blend

For Flour Shop’s Rainbow Explosion mix, it’s all about color. “I started breaking down my sprinkles originally by color just because I’m such a visual person,” Kassem says.

The Rainbow Explosion mix uses eight different colors of sprinkles that the bakery buys separately and mixes in-house. “I started creating the rainbow, and I realized that adding some white really broke it up and I loved that,” she says.

Then she added sixlets — large sugarcoated milk chocolate balls — to “have more of a piñata effect.”

The last two ingredients help add different textures.

“I added the nonpareils, which are the tiny ones that like to dance around and make a mess,” Kassem says. “Lastly, I had meteors, which are almost like mini coated chocolate chips. Those are just the perfect crunch.”

If you wanted to use Flour Shop’s Rainbow Explosion mix without sourcing all the different ingredients, the bakery is selling its signature blend at Williams Sonoma starting May 2 online and May 13 in stores, according to Kassem.

Making it your own

If you are looking to put your own spin on the sprinkle mix, Kassem recommends using “whatever your favorite things are.”

“You could put different M&M’s, you could put anything really that you find at any grocery store,” she says. “I think that whatever you’re really excited about is what you should be putting in the cake. [We’re] really encouraging people to put whatever they want in it. As long as it can be stored in the refrigerator, it can be anything, any type of candy.”

Thinking outside the box is also key.

“I live by the age of my inner child, I’m never growing up,” Kassem says. “I think that when you’re young, you don’t really see limits. I think holding on to that is more important than anything else. What I’m recommending in the book is just some of my signature things, but I would love to see people just creating from their own imagination.”

Trial and error

Still, there are some things to avoid putting in your cake.

“We have tested it with different things. Definitely marshmallows aren’t the way to go,” Kassem says. “I definitely would also not put gummies in there, they tend to get stuck together.”

If an experiment fails, the cakes are forgiving, too.

“If you mess up you can just cover it in sprinkles and everyone will love it anyway,” Kassem says. “I think frosting is like glue and sprinkles are like Band-Aids.”


Amirah Kassem celebrates the release of "The Power of Sprinkles" with a book signing and face paintings on Saturday from noon-3 p.m. at Flour Shop | 177 Lafayette St.

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