Rainbow sprinkles turn anything into a party. How else can you explain the effervescent popularity of Funfetti cake? When we threw a backyard S'mores birthday party for my sister, I knew that sprinkles had to be part of the plan. And what better place to put sprinkles, but in a marshmallow? Colored sugar, mixed into fluffy sugar, toasted on a S'more. Sounds about right to me.
The basic method for marshmallows goes like this: Mix some water and gelatin and set aside. Then heat sugar and corn syrup until it reaches a certain temperature, and pour this over the gelatin. Mix in your handy stand mixer for a little while, and voilá! Sticky marshmallow mixture. Spread it in a pan, let it cool, then cut it into squares. As long as thermometers don't terrify you and you have a sturdy mixer, these are easier than cake.
And these particular marshmallows actually taste quite a bit like cake. I added a hefty dose of vanilla and some butter flavoring, and mixed in lots of sprinkles. They taste a little buttery and very mellow, with crackling pops of sprinkles in each bite. They're sugary and a little over-the-top, and oh-so fun. You could even use homemade sprinkles.
At the party, we stacked a few of these marshmallows high on a S'more and sang Happy Birthday — and my sister agreed it was even better than cake.
Birthday Cake Marshmallows with Sprinkles
Makes about 64 1-inch-square marshmallows
3/4 cup powdered sugar
1/4 cup cornstarch
3/4 cup multi-colored sprinkles, divided
3 tablespoons (usually 3 packets) unflavored powdered gelatin
2 tablespoons vanilla extract
2 teaspoons butter flavoring
1 1/4 cup sugar cane syrup or corn syrup
1 1/2 cups granulated sugar
1/4 teaspoon salt
Spray an 8x8-inch pan with baking spray. Use a paper towel to wipe the pan and make sure there’s a thin film on every surface, corner, and side.
Whisk together the powdered sugar and cornstarch and use a wire sieve to tap a thick layer of the cornstarch mixture over the bottom of the pan. Scatter a layer of sprinkles, about 2 tablespoons, over the cornstarch.
Put the gelatin in the bowl of a stand mixer. Combine 1/2 cup plus 2 tablespoons cold water, vanilla, and butter flavoring in a measuring cup and pour this over the gelatin while whisking gently with a fork. Continuing stirring until the gelatin reaches the consistency of applesauce and there are no large lumps.
Pour 3/4 cup water into a measuring cup, then add the corn syrup. Pour into a 3-quart or larger saucepan, and stir in the sugar and salt. Bring to a boil over medium-high heat.
As it’s coming to a bowl, occasionally dip your pastry brush in water and brush down the sides of the pot. This prevents sugar crystals from falling into the liquid, which can cause the syrup to crystallize. If you don’t have a pastry brush, cover the pan for 2 minutes once the mixture is at a boil so the steam can wash the sides.
Do not stir the sugar once it has come to a boil or it may crystallize.
Clip a candy thermometer to the side of the sauce pan and continue boiling until the sugar mixture reaches about 247°F to 250°F. Take the pan off the heat and remove the thermometer.
With the mixer on low speed, gently and carefully pour the hot sugar syrup down the side of the bowl into the gelatin. The mixture may foam up — just go slowly and carefully. When all the syrup has been added, cover the bowl with a cloth and increase the speed to high (the cloth protects from splatters).
Whip for 12 minutes on one of the highest two speeds. When ready, the mixture should look like glossy meringue and form high, sharp peaks if you touch it with your finger. If you lift your mixer whisk and let the mixture fall in ribbons, those ribbons should stay distinct and mounded up on the surface for several moments at least.
Add 1/2 cup sprinkles and briefly pulse the mixer to incorporate them. Lift the whisk partway out of the bowl and pulse again it spins off as much marshmallow mix as possible.
Using a stiff spatula, scrape the marshmallow mixture into the prepared pan. It will very thick and sticky, so don’t worry about getting every last bit out of the bowl. Just get as much as you can.
Wet your fingers and smooth the top so it’s even. Sprinkle the top of the cured marshmallow with the remaining sprinkles. Let the mixture sit out uncovered for at least 2 hours to set and cure.
Sprinkle the top of the marshmallow mixture with more of the powdered sugar and cornstarch mixture. Turn the marshmallow out onto your work surface. Use a spatula to pry it out of the pan if necessary. Sprinkle more powdered sugar mixture over the top.
Using a sharp knife or pizza wheel, cut the marshmallow into 1-inch cubes. It helps to dip your knife in water every few cuts. Toss each square in the powdered sugar mix so all the sides are evenly coated.
Marshmallows will keep in an airtight container at room temperature for several weeks. Leftover marshmallow coating can be stored in a sealed container indefinitely.