With two layers of #rainbow cake, a bright fondant icing, and oodles of colorful #sprinkles, these bite-size Funfetti Petit Fours are ready to celebrate! #celebration #cake #funfetti | FeastInThyme.com

Rainbow Cake Funfetti Petit Fours with Vanilla Fondant Icing

Bring a smile to everyone’s face with a tray of delicious Funfetti Petit Fours! Two layers of rainbow cake are stacked with a bit of berry jam & draped in vanilla fondant icing. With a finishing touch of colorful sprinkles, these sweet confections are a welcome addition to any celebration. 

Disclaimer: This post contains affiliate links, and I will earn a commission if you purchase through those links at no additional cost to you. All thoughts and opinions are my own. 

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There are a few things I know for sure in this life:

  • Everyone loves miniature versions of their favorite foods.
  • Nothing screams “celebration” like rainbow sprinkles and funfetti cake.
  • No true tea party is complete without a platter of beautifully decorated cakes.

With two layers of #rainbow cake, a bright fondant icing, and oodles of colorful #sprinkles, these bite-size Funfetti Petit Fours are ready to celebrate! #celebration #cake #funfetti | FeastInThyme.com

With two layers of #rainbow cake, a bright fondant icing, and oodles of colorful #sprinkles, these bite-size Funfetti Petit Fours are ready to celebrate! #celebration #cake #funfetti | FeastInThyme.com

In the tradition of these tiny Victorian Era confections, this recipe for Rainbow Cake Funfetti Petit Fours checks all the boxes. They start with a fluffy white sponge cake splashed with the iconic rainbow colors of a commercial funfetti cake. Two little squares are stacked with the tiniest dab of berry jam to hold them together, and then the whole tiny cake is draped in a rich, homemade fondant icing that is lightly flavored with vanilla and dyed a vibrant blue. Each bite is an explosion of color and sweet delight.

Fun for kids of all ages and nostalgic for us adults, these Funfetti Petit Fours with Vanilla Fondant Icing will add a whimisical touch to any party. Make up a batch and enjoy the smiles!

Jump to Recipe

Funfetti Petit Fours arranged on a marble platter with two silver spoons. | FeastInThyme.com

Rainbow Cake Funfetti Petit Fours

When I was young, I was lucky enough to have one of the original American Girl Dolls – Victorian Era Samantha. Her story was set in turn of the century New York State, and I read all the books and had a good number of her tiny Victorian accessories. Surprising no one, I particularly loved the incredibly realistic replicas of food and drink, but none as much as the delicate petit fours. I was enamored with these little cakes that my mom even found some at a local bakery for one of my birthdays. I can still remember the adorable roses on top of the white and pink fondant icing. They were perfectly square, and perfectly delicious.

The term petit four means “small oven” in French, which comes from the way these French pastries were cooked in the lingering heat of large brick ovens in the 18th and 19th centuries. While petit fours can historically take a number of shapes and forms, the most recognizable in America today is a glace (“glazed”) petit four – a tiny (usually square-shaped) cake decorated with icing or fondant.

A display of Funfetti Petit Fours, some one a platter and a few on individual plates. | FeastInThyme.com

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Vanilla Fondant Icing

If you watch any popular baking shows or ever shopped for an elaborate wedding cake, you’ve heard of fondant icing. In commercial baking, it’s often made thick enough to lay in sheets or designed to be moldable like clay. This kind of structural ‘rolled fondant’ looks beautiful, but usually isn’t very tasty.

The Vanilla Fondant Icing in this recipe is a little different. Based on a delicious recipe by Rose Atwater, this poured fondant icing has a base of powdered sugar, white chocolate, and corn syrup. It cools and hardens quickly once it’s poured over the cakes, taking on a smooth, glossy finish that looks professional (no matter your actual expertise!). Best of all, it has a lovely, simple flavor that is sweet but not cloying. Leave the icing white or add food coloring (like the pretty blue I show here) and accessorize with a variety of sprinkles for a fun, festive look.

Funfetti Rainbow Cake in a sheet pan. | FeastInThyme.com

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Funfetti Cake From Scratch: Easier Than You Think!

If you only know funfetti cake from pre-packaged cake mixes and other processed foods, you might be surprised to know that there is an entire cult of rainbow devotees dedicated to recreating this multi-colored phenomenon in their home kitchens. Molly Yeh (of My Name is Yeh) is particularly famous for her versions of funfetti cake. I adapted her recipes published in Cherrby Bombe: The Cookbook and Molly on the Range in order to make the thin, stackable sponge cake used below.

The cake itself is very light and almost white in color, allowing the rainbow sprinkles to shine. As Molly notes in her recipes, using artificially colored rainbow sprinkles is a must. I trust her judgement that all-natural versions, despite her best efforts, just don’t achieve the iconic, colorful look of traditional funfetti.

Funfetti Rainbow Cake cut into squares. | FeastInThyme.com

Traditional sponge cake is very airy – think of a perfectly made fluffy cupcake. In order for this rainbow sheet cake to hold it’s shape when cut into squares, it has to have a little more structure. The end result is a cake that tastes almost like a cross between a nice sponge and a sugar cookie – light and fluffy on the inside with a thin crispy crust on the outside.

Use a ruler to cut the rainbow sheet cake as uniformly as you can. If a few aren’t perfect, don’t worry. It’s easy enough to match up even imperfect squares, and the fondant icing will bridge any gaps in uniformity you might notice.

Squares of Funfetti Rainbow Cake, stacked up with berry jam in the center. | FeastInThyme.com

To hold the two layers of cake together, just add the smallest drop of your favorite berry jam. I used a homemade mixed berry jam, but a nice strawberry jam would also be delightful.

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A batch of Rainbow Cake Funfetti Petit Fours will delight guests and surprise loved ones. These bite size confections are as delicious as they are colorful.

Funfetti Petit Fours on a cooling rack, the fondant icing dripping over them. | FeastInThyme.com

Rainbow Cake Funfetti Petit Fours with Vanilla Fondant Icing

With two layers of rainbow cake, a bright fondant icing, and oodles of colorful sprinkles, these bite-size Funfetti Petit Fours are ready to celebrate! 

Sponge cake adapted from various versions of Molly Yeh’s Funfetti Cake Recipe

Keyword cake, fondant, funfetti, icing, petit four, rainbow, sprinkles
Prep Time 40 minutes
Cook Time 20 minutes
Cooling time 30 minutes
Total Time 1 hour
Servings 40 bite size cakes

Ingredients

Funfetti Sponge Cake

  • 1 ¼ cup all purpose flour
  • 2 tablespoons cornstarch
  • ½ teaspoon salt
  • 1 teaspoon baking powder
  • ½ cup 1 stick unsalted butter, room temperature (plus more for greasing the baking sheet)
  • ¾ cup granulated sugar
  • 2 egg whites
  • 2 tablespoons vegetable oil
  • 2 teaspoons vanilla extract
  • 1/3 cup almond milk
  • 1 cup artificially colored rainbow sprinkles, plus more for decorating
  • ½ cup mixed berry jam

Vanilla Fondant Icing

  • 6 cups powdered sugar
  • ½ cup water
  • 2 tablespoons light corn syrup
  • ¾ cup white chocolate melting wafers
  • 3-4 drops food coloring, blue or the color of your choice (optional)

Kitchen Supplies

  • 9x13 inch non-stick baking sheet
  • Standing mixer or a hand mixer
  • Rubber spatula
  • Ruler

Instructions

Mix the Funfetti Batter

  1. Heat oven to 350 degree F. Line a 9 inch by 13 inch non-stick baking sheet with a layer of parchment and then grease the parchment and any exposed pan thoroughly with butter.

  2. Whisk together the dry ingredients (flour, cornstarch, salt, and baking powder) in a large bowl. Set aside.

  3. In the bowl of a standing mixer, cream together the butter and granulated sugar until fully incorporated and very light and fluffy (about 5 minutes).

  4. In a small bowl, beat the egg whites thoroughly with a whisk until they become frothy. This will aerate the egg whites for a lighter batter. Beat the aerated egg whites into the butter-sugar mixture one small tablespoon at a time, making sure the egg is fully incorporated before adding more. The batter should be very light and airy. Beat in the vegetable oil and the vanilla extract one at a time.

  5. Turning the mixer to low speed, mix the dry ingredients into the wet ingredients one cup at a time. Remove the bowl from the standing mixer and gently fold the rainbow sprinkles into the batter with a flexible rubber spatula. Be careful not to mix too rigorously, as doing so could break the air bubbles you’ve created with all of your mixing and whisking.

  6. Pour the batter into the prepared baking sheet and spread it into a smooth, even layer. Bake 15-20 minutes, until the sponge cake is light golden in color and a toothpick can be inserted and come out clean. Allow the cake to cool, and then freeze for 30 minutes to overnight.

Cut and Assemble the Cake Layers

  1. Once the sponge cake has chilled, invert the pan onto a large cutting board or other working surface, peeling off the parchment paper (you may need to loosen the edges where the cake meets the pan). With a large, sharp knife, cut off the ragged edges of the cake to leave a nice, clean edge. Using a ruler, cut the cake into uniform squares, 1 inch by 1 inch.
  2. Match up the cake squares as best as you can. Place a very small dab of mixed berry jam on one square and press the second square on top of it, making a tiny cake “sandwich”. Repeat until all the cake squares are paired up. Arrange the cakes on a cooling rack set over a large piece of parchment paper, leaving a bit of space between.

Make the Fondant Icing

  1. Bring a pot of water to a boil, and set a heatproof glass bowl over the pot to make a double boiler. Add the sugar, water, corn syrup, and vanilla extract to the  bowl and carefully whisk them together until smooth (it should reach a temperature of about 92 degrees F). Stir in the white chocolate wafers until melted and smooth.

  2. Careful not to burn yourself, remove the glass bowl from the pot of boiling water and set on a trivet or folded kitchen towel. If you want a colored fondant, add a few drops of your chosen food coloring a little at a time until you achieve the desired shade of icing (I like to add 3-5 hearty drops for a nice dark color).

Assemble the Petit Fours

  1. Prepare your work station next to the cooling rack of tiny cakes. You'll want a few bowls of different decorating sprinkles, the bowl of fondant icing, and a spoon. 

  2. While the fondant icing is still warm, pour spoonfuls over the cakes, letting the icing drip over the sides and onto the parchment underneath. You can try to cover the cakes completely, or just do a partial “drape” of icing, like the majority of the petit fours pictured here. Work quickly and in batches, decorating with sprinkles as you go. The icing should smooth out and cool quickly.

  3. Leave the decorated Funfetti Petit Fours to set for 20-30 minutes. Store in a single layer in a sealed container for 2-3 days, or in the refrigerator for 4-5 days. Serve arranged on a pretty platter with tea, coffee, and probably a good number of lacy doilies for good measure.

Recipe Notes

The Lightest, Fluffiest Batter: The recipe here is formulated to make a very pale, very light sponge cake. The key to the color is to use only the lightest white ingredients (egg whites, white flour, white sugar, etc.). The key to the texture is in aerating the batter as much as possible - whisking the egg whites until frothy and creaming the butter and sugar until fluffy. Avoid using a rigid spoon when mixing in the sprinkles, as a flexible spatula is less likely to break the air pockets you've painstakingly created.

Artificially Colored Sprinkles Only: The natural kind just won't "bleed" dye like the processed ones.

Pouring on the Fondant Icing: The icing will start to harden quickly. Work in batches, sprinkling the decorating sprinkles before it dries so that they stick. Once complete, don't move until the icing has fully hardened or you may leave fingerprints. 

Platter of Funfetti Petit Fours. | FeastInThyme.com

 

 

With two layers of #rainbow cake, a bright fondant icing, and oodles of colorful #sprinkles, these bite-size Funfetti Petit Fours are ready to celebrate! #celebration #cake #funfetti  | FeastInThyme.com

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