Introduction: Rainbow Ice Cream Cake Recipe

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I created this rainbow ice cream cake for Penolopy Bulnick's birthday. Last year I made her a traditional Dairy Queen style ice cream cake, but I wanted to raise the bar this time. If there's anything you need to know about Penolopy, it's that she LOVES sweets. And rainbows. So I decided after lots of trial and error that I wanted to make a rainbow ice cream cake that tasted like candy. :D

The secret? Kool-Aid!

Kool-Aid gives this cake a slightly sour candy flavor (like Sweetarts!) while the white chocolate ganache filling keeps the sourness from being overpowering. It works perfectly together.

Plus, it's not as heavy as a traditional ice cream cake - the citric acid in the Kool-Aid really makes it taste nice and light, like sherbet. :)

Step 1: Ingredients + Tools

for the cake:

  • 2 x 1.5 quart containers of vanilla ice cream
  • 4 packets of Kool-Aid, whatever flavors/colors you want
  • 1/2 cup whipping cream
  • food coloring as desired to increase the saturation of the colors

for the white chocolate ganache:

  • 16 oz white chocolate
  • 1 cup whipping cream

This makes just enough to do the layers - if you would like your cake more sweet, I recommend just going all out and doing 24 oz white chocolate and 1 1/2 cups heavy whipping cream. Leftover ganache is never a bad thing, anyway. ;)

for the whipped frosting:

  • 2 teaspoons unflavored gelatin
  • 2 tablespoons cold water
  • 2 cup whipping cream
  • 1/2 cup powdered sugar, sifted


Step 2: Line Your Cake Pans and Plan Your Cake

First things first: line the cake pans with aluminum foil. Try to make it conform to the pan as much as possible. If it doesn't go all the way over the edges in a couple spots that's okay.

(I guess you could also use plastic wrap for this, but plastic wrap and I always end up fighting so I decided to not cuss a lot while doing this part.)

Once that's done, decide which colors you want and in what order. You're going to be building the cake in two halves that you'll put together, so each pan will have two layers in it.

Step 3: Mix Up the Koolaid

Take two packets of Kool-Aid and pour them into two tiny bowls. Add two tablespoons of the heavy cream to each bowl and mix well.

Step 4: Divide the Ice Cream and Color It

I suggest just cutting your container in half. Easier to do than trying to measure out three cups into each bowl. :D (I'm using about 3 cups of ice cream to a packet of Kool-Aid - just in case your ice cream doesn't come in a 1.5 quart container.)

Once it's cut in half, place each half in its own bowl. Add the Kool-Aid and cream mixture and stir well to combine. (If the ice cream is really cold, this can be tricky. Let it sit a couple minutes to soften and try again. Just don't let it defrost all the way!)

For the yellow/lemon Kool-Aid, I did add more food coloring to it. The color is very light! Everything else is colored as-is.

Step 5: Pour and Chill!

Spread the now Kool-Aid-y ice cream into the bottom of your pans. Try to get it as flat as possible. Spatula skills!!

Once that's done, pop it in the freezer for a couple hours. You want the top to be totally set for the next part.

Step 6: Make the Ganache

Do this right near the end of the chilling period for the ice cream so you've got it ready to go on. :)

Heat your whipping cream in the microwave until it reaches boiling - for me this takes about three minutes.

Place your white chocolate chips in a large bowl and pour the cream over. Mix together until it's totally combined.

At this point, you can pop it in the freezer for a half hour or so. You need the ganache to be cool and slightly thick, but not stiff.

Once it's cooled, beat with a stand or hand mixer for 3-5 minutes, or until it's nice and fluffy.

Step 7: Cover the First Layer With Ganache and Chill Again

Divide the ganache into three parts as best you can.

You'll use two of the three parts to spread onto the chilled ice cream. Just try to get it as flat as possible.

Then place the pans back into the freezer for about a half hour or so - just until the ganache is nice and firm.

Put the rest of the ganache in the fridge while the pans are chilling.

Step 8: Mix the Kool-Aid for the Second Layers

Combine the Kool-Aid packets with two tablespoons of cream and mix well.

Step 9: Mix the Kool-Aid and Ice Cream

Cut another container of ice cream in half and put it in bowls. Repeat the mixing process. :)

Step 10: Chill the Second Layer of Ice Cream

Spread the ice cream mixes you just made on top of the ganache layers.

Flatten them out and pop them back in the freezer for another couple hours to firm up.

P.S. I also very much recommend putting the item you're going to using to serve/display the cake in the freezer now, too. I'm using a large plate.

Step 11: Build the Cake!

Pull the ganache out of the fridge first - if it's firmed up all the way, microwave it in short (5-10 second bursts) just until you can easily mix it.

Then pull the two pans out of the freezer.

Pull the ice cream out of the pan using the aluminum foil. Peel the foil off and place the ice cream layers on the serving plate.

Now, apply the white ganache to the top of the bottom layer, spreading it out as evenly as you can. Save a teensy bit to fill in any holes.

Remove the second set of layers from the pan, remove the foil, and place on top.

If there are any large gaps, use the white chocolate ganache to fill those in. :)

Step 12: Chill the Cake

Chill the whole cake for as long as you can. I chilled it overnight. :)

The longer you chill, the more stable it will be, which will make frosting easier. At the bare minimum, give it three hours.

Step 13: Make the Stabilized Whipped Cream Frosting

Combine two teaspoons of plain gelatin and two tablespoons of cold water in the smallest sauce pan you have. Mix together until the gelatin has absorbed all the water and the mix has swelled in size.

Then heat it over medium heat, stirring constantly, until all the gelatin has dissolved. (It will smell bad, so don't worry if this is your first time doing it! That smell won't hang around after it's combined.)

Pour the gelatin into a small bowl and set aside to cool.

Pour two cup of cold whipping cream into a large bowl and sift 1/2 cup of powdered sugar over it. Beat the whipping cream on high for a couple minutes or just until it starts to thicken. (Just until the beaters start leaving lines)

Then, check your gelatin. Make sure it's nice and cool but NOT firmed up.

Begin to beat the cream again on low while pouring in the gelatin. Once the gelatin is in, beat again on high until you get stiff peaks. (Shown in the second photo)

P.S. In my experience this cream never gets quite as stiff as traditional whipped cream, but that's okay! Once it his the cold cake it will firm up.

Step 14: Frost the Cake + Chill Again

Pull the cake out of the freezer and frost! Try to work fast so the cake doesn't start to warm up.

It's easiest to pop a blob of the frosting on top and then spread it down the sides.

Once it's all frosted, put it back in the freezer for at least a half hour. This will fully set the frosting.

Step 15: Cut and Enjoy!

This is the absolute best part of this project - cutting into it and seeing all your hard work pay off!

Use a knife dipped in hot water and then dried to get nice clean cuts. :)

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