Earth Eats: Real Food, Green Living

Rainbow Layer Cake

Cookie Monster would definitely consider this cake a “sometimes” food, based on the effort alone!

multicolored cake with white frosting

Photo: Natalie DeWitt

This cake is kind of like a fruity, citrusy explosion in your mouth, tempered by the lightness of the whipped cream.

I don’t usually recommend using boxed cake mixes because of all the preservatives and chemicals, but for this recipe, it’s necessary—there’s something about those chemicals and preservatives that keeps this cake firm, moist and overall delicious. I augment my use of the boxed mixes with organic, low fat sour cream and local, farm fresh eggs. Besides, Cookie Monster would definitely consider this cake a “sometimes” food, based on the effort alone!

Rainbow Layer Cake

By Natalie DeWitt

Ingredients for Cake:

  • 2 boxes (18 ounces) Pillsbury White Cake Mix
  • 2 cups all purpose flour
  • 2 cups sugar
  • 1 1/2 teaspoons salt
  • 2 cups water*
  • 1/4 cup vegetable oil
  • 1 tablespoon vanilla
  • 2 cups low-fat sour cream (go organic and/or local!)
  • 8 large egg whites (go organic and/or local!)
  • Pint of heavy whipping cream
  • Coconut, or other decorations

Ingredients for Flavors:

  • Frozen raspberries, blackberries and blueberries, thawed
  • 2 -3 lemons
  • 2-3 limes
  • 2 blood oranges
  • Food colorings, if you aren’t happy with the colors of the layers

Equipment:

  • A few cake pans of equal sizing (8 inch pans are ideal)
  • Cooking spray
  • A little extra flour
  • Cooling racks
  • Fine mesh strainer
  • Spatula
  • 7 bowls of equal size
  • 6 bowls to collect fruit juice

Directions:

  1. Prep your pans, and your patience: spray your pans, even if they’re non-stick, with cooking spray. Add a tablespoon of flour to the pans and swirl it around, covering the bottom and sides of the pan. Lightly tap the pans on the side of your sink (with the pan over the sink, otherwise you will regret your decision to make this cake before you even begin.) This is important if you want your cake layers to come out in one piece!
  2. Preheat your oven to 325 degrees.
  3. Place all dry ingredients in a large mixing bowl and stir together with wire whisk. Add everything else and mix on low for 5 minutes.
    *Note about water: this is where things get tricky. Overall, the recipe requires 2 2/3 cups of liquid (ie, water, berry juice, etc). I initially start by adding 2 cups of water to moisten the batter and go from there.
  4. Get out your kitchen scale, or 7 bowls that are the same size and shape (my white cereal bowls work well for this… that doesn’t help you really, though). Divide the batter equally amongst the seven bowls. These will be your rainbow layers! Add one color of juice to one bowl, until the color looks bold and bright, continuing with the other flavors/colors. The color will darken as it bakes, so not TOO bold and bright. Stir.
  5. Remembering ROY G BIV is important here. Don’t be afraid to experiment with other flavors and colors.
  6. six cake layers with whipped cream in between each layer

    Photo: Natalie DeWitt

    Experiment with different flavors and colors for the layers!

    Red: Raspberries. Make sure your raspberries are thawed, and collect as much juice as you can from them. I like to give them a good smash while they’re in the bag, and then pour them into a fine mesh strainer, pushing the juice through with a spatula. No one wants raspberry seeds in their cake.
    Orange: Blood oranges. Juice those oranges. Zest one of them, too. Seeds are bad here, so toss those in the trash.
    Yellow: Lemons. Juice two and zest one.
    Green: I have no idea. I couldn’t think, for the life of me, what to flavor this layer that came from nature besides lime. If you have any ideas, add them in the comments below! Otherwise… green food coloring it is, along with some lime juice and zest.
    Blue: Blueberries. I Follow the same procedure as the raspberries. Make sure you rinse your strainer between smooshings.
    Indigo: I don’t accept this as an actual color, but I went with a combination of blueberries and blackberries for this layer. I ended up omitting it from the final cake because it looked too similar to the blue and violet—this is your cake now, experiment, and make the final decision on whether to include it! I think I’ll try grape juice in the future, but no one said, “Hey, where’s indigo?” so I think you’ll be safe if you omit it. If you make this decision early on, you can just work with 6 bowls, and add more batter to the others.
    Violet: Blackberries! Follow the same procedure as the raspberries and blueberries. Seeds are bad here, too. They know just how to get lodged in your molars.

    *Note here: I did end up using a couple of drops of food coloring for some of the layers, just to give them a little more distinction. It’s MOSTLY naturally dyed. Adding this is entirely up to you.

    white frosted cake

    Photo: Natalie DeWitt

    I suggest decorating this cake right before you serve it, because the cream will weep and become destabilized.

  7. Okay, now you have 6 or 7 bowls staring back at you, and you’re wondering….”wait, I only have 2 pans, how am I going to bake all of these?” The answer to that question is the first rule of taking on this recipe: patience. I suggest starting with red and orange, but you can be a non-traditionalist and start with violet and blue if you’d like — regardless, you’re going to bake each layer for about 15 minutes (you can put both or however many pans you have in at one time), or until a toothpick poked in the center comes out clean. The cake layers will be thin, so keep an eye on those first few you put in to get an accurate baking time.
  8. Once the first cakes are done, let them cool for 5 minutes before removing them from the pan. Take a knife and run it around the edges to release it, and put one of your cooling racks on top of the cake. Inver the cake onto the cooling rack. Cheer, or cry, depending on how well you greased and floured the pan. Wash the pans, re-grease, and re-flour. And then you’re on to yellow and green! Continue until all the cakes are done.
  9. a slice of rainbow cake

    Photo: Natalie DeWitt

    Use raspberries, blood oranges, lemons, limes, blueberries and blackberries to color and flavor your cake.

  10. While you’re waiting for what feels like forever for the cakes to cook and cool, you can whip your cream. I suggest decorating this cake right before you serve it, because the cream will weep and become destabilized. If you wait to decorate, you can store your cakes, in reverse order. Remember you’ll have unassembled them working from the bottom up when you place the cream between the layers — smart, right? Place a sheet of plastic wrap between each cake.
  11. Decorate to your heart’s content. I like to leave it white, so the layers inside are a surprise to everyone. You would think that all those flavors wouldn’t go well together, but it’s kind of like a fruity, citrusy explosion in your mouth, tempered by the lightness of the whipped cream. You’re friends will be impressed. You’ll be impressed with yourself. It’s a win-win.

Read More:

  • Cookie Monster Changes His Tune (CBS News)

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Natalie DeWitt

Natalie DeWitt has degrees from Indiana University in Secondary Health Education, School and College Health Programs, and is now a PhD student minoring in food studies. Her primary research areas focus on virtual food, food identities, and school food environments. She is a self-taught baker and cook.

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  • Kelsey

    spinach! it works.. i know some one who made a tinkerbell cake with spinach and you could not taste spinach

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