When I met Jessica Siskin, she was elbows deep in a blue enameled pot, stirring a bag of mini marshmallows over low heat, melting them to the perfect consistency. "You don't want to let them melt too much," she explained matter-of-factly. "When you let your marshmallows melt down to a liquid, that is how to end up with those hard Rice Krispie Treats you break your teeth on." Siskin would know. She's the founder of Misterkrisp, which started as an Instagram account filled with whimsical sculptures made of Rice Krispie Treats, until October 2013, when Siskin turned that hobby into a business. Yes, that means Siskin makes 3D edible sculptures out of breakfast cereal for a living, and yes, it's as delicious—and messy—as you might expect.

When you watch Siskin work, you realize what good building material Rice Krispie treats really are, especially in her capable, greasy hands. (She coats her hands with cooking spray before molding the mixture of cereal and melted marshmallows, explaining to the captive audience on Facebook Live, "that'll allow me to mold these treats directly" with minimal sticking.) In less than ten minutes, Siskin had sculpted and decorated a Santa Claus emoji, much to the delight of the online audience, using just four ingredients: Rice Krispies, mini marshmallows, butter, and icing.

She wiped her hands of the excess cooking spray as she explained to me that the holiday season is apparently primetime for custom Rice Krispie Treats, especially since, for the second year in a row, she partnered with Kellogg's on a campaign called Treats for Toys. The concept is simple. Make some Rice Krispie Treats, post a picture to Instagram, and use the hashtag #Treats4Toys. "When you use the hashtag, post a picture of any treat on social media and use the hashtag #Treats4Toys, they donate a toy to a child in need through Toys for Tots," she explained.

To celebrate this partnership, Siskin was tasked with making an edible holiday window display solely out of Rice Krispie Treats. The breakfast cereal-centric window display, currently on display at 225 East 57th Street in Manhattan until Monday, December 12, is something of an island of misfit Rice Krispie Treats toys, and it's maniacal in the most wonderful way, easily rivaling the glitzy over-the-top shows put on by the other department stores, located less than ten blocks away. 

There's a basketball, a skateboard, and a teddy bear with a red bow around its neck, as well as a unicorn toy and an oversized toy robot, right at the front. There are even gingerbread man cookies and sticks of butter, somewhat ironically made out of butter and breakfast cereal. Even the walls of the display are coated in spray painted Rice Krispies, and if you look closely enough, there's a little Golden Retriever hiding under the table. "It’s my family’s dog, Posie, when she was a puppy," Siskin said, adding, "I’m going to ask if I can keep it. I actually have to talk with them about that. I should put it under my coffee table."

Siskin made all of these edible sculptures over the course of a very long week. "To make the actual treats on the table, I used two cases. So that’s 24 18-ounce boxes. We could do the math later." (I did do the math. That’s about 27 pounds of Rice Krispies cereal.) "An 18-ounce box, on a regular day, will last me four projects, " she said. "I was dumping entire 18-ounce boxes in my pot." The puppy alone took four 18-ounce boxes, by Siskin's best estimates.

Though Siskin is no stranger to making strangely shaped Rice Krispie Treats—like, say, a portrait of Gucci Mane—this window display presented its own challenges, many of them structural. The robot, for instance, was heavy and needed to be assembled at a separate window design studio. Siskin tried to find other ways to provide scaffolding to the Rice Krispie Treats. "I went to Michael’s on Black Friday, and the whole store was 40 percent off, and I bought all the styrofoam, thinking I’d be able to use styrofoam in the middle, but treats don’t stick to styrofoam. Good to know for your Rice Krispie-sculpting needs,” she said. “Honestly, it only really sticks to itself, is what I’ve learned. It’s even hard to get it to stick to cookies and things like that."

That's why, in the end, most of the treats on display are made of layers and layers of Rice Krispie Treats, stacked on top of each other. "I keep saying that I would like to cut the basketball down the middle once we’re done with it because what I did was I started with a small ball and the just every time I had extra, I layered it, so it’s probably twenty colors in there. So it’s going to be really cool inside. Like a Gobstopper, like a jawbreaker."

It's a lot of trial and error, and the only way to get good at this very niche art form is by doing it. More often than not, though, Siskin picks up these innovative Rice Krispie Treat-making techniques from her followers. "I learn things sometimes from seeing how my customers make things, because sometimes I think I’m overthinking it, so watching the way other people do it—I learn a lot."

But Siskin is a firm believer that anyone can make a Rice Krispie Treat, even one that looks like a toy robot or a Santa Claus emoji. "Honestly, I’ve had so many people try to do it at home and say to me, ‘Wow, it really is easier than it looks.’ So that’s cool." Her best pro-tip for optimal sculpting, though, might be that cooking spray on her hands. "Really changes your life. I don’t even know how I came up with that."