Pastel Rainbow Cake [and a VIDEO!]

Embellish a cake mix to make a sturdy and moist cake that is perfect for decorating. Vanilla Buttercream tinted beautiful pastels and covered with white chocolate ganache will make one beautiful springy cake perfect for a baby shower.

pastel rainbow cake

Today we are celebrating the first baby of our blogger friend Joanne of Fifteen Spatulas. Baby James made his appearance a few weeks ago and today we are celebrating him and Joanne like we would if she lived closer to us – with food! Lots of blogger friends are throwing them a virtual baby shower and there are lots of amazing recipes floating around the Interwebs today in their honor. My contribution – Pastel Rainbow Cake with White Chocolate Drip.

Joanne – I am so happy for you and Pete and know that you are going to be amazing parents. Baby James is very lucky to have you both.

pastel rainbow cake

I don’t usually make fancy cakes because I don’t have the patience for it. I start with good intentions and get bored halfway through. Then my cake looks terrible and I don’t make another cake for a year. But it is something that I really want to get better at. This cake was so much fun that it might have been the gateway cake I needed to really get into cake decorating.

I used an embellished cake mix recipe for the layers. You can use whatever recipe you like, but I have found that cake mix (with a little help) is really consistent and makes very sturdy layers that are moist and delicious, but also hold up well for decorating and slicing.

pastel rainbow cake

I’m going to put it out there – I am really proud of this cake. It is inspired from a few different cakes that I have seen floating around YouTube and this is my take on a rainbow cake with a chocolate drip. Above are the colors that I used to tint my frosting. I prefer Americolor because I like the squeeze bottle over the jar, but any gel color will do.

  • Fuschia
  • Orange
  • Lemon Yellow
  • Electric Green
  • Electric Blue
  • Electric Purple

pastel rainbow cake

When you are cleaning up the edges of the cake, save the scrapings. You are going to use it later to pipe stars on the top. (Just like the ones below.)

pastel rainbow cake

You can watch how I put this cake together below.

To see what other deliciousness is being served at Joanne’s Virtual Shower, click the links below:

Italian Sub Sandwich Roll-ups from Michael of Inspired by Charm
Smoky Roasted Red Pepper Sun Dried Tomato Hummus from Jeanette of Jeanette’s Healthy Living
Creamy Sweet Potato Soup from Sadie of Dairy Good Life
Whipped Goat Cheese & Blueberry Balsamic Crostini from Meseidy of The Noshery
Rosemary Flatbread with Baked Goat Cheese from Heidi of FoodieCrush
Spring Herb Cream Cheese Appetizer Cups from Rachel of Rachel Cooks
Crostini with Almond Ricotta and spicy olive tapenade from Heather of HeatherChristo

Fruit Freeze from Deborah of Taste and Tell
Mint Lemonade from Trish of Mom On Timeout
Ginger Lemonade from Kathy of Panini Happy

Chocolate-Covered Rice Krispies Treats from Julie of The Little Kitchen
Orange Fluff from Jamie of My Baking Addiction
Chocolate Peanut Butter Pretzel Brownies from Susannah of Feast + West
Mini Ombre Heart Cookies from Bridget of Bake at 350
Mini Coconut Pound Cakes from Mary of Barefeet In The Kitchen
Yellow Sheet Cake with Chocolate Sour Cream Frosting from Jennifer of Savory Simple
Unicorn Shaped Cookies from Jessie of CakeSpy
Oreo Cheesecake Bites from Brenda of a farmgirl’s dabbles
Lemon Blueberry Bread from Glory of Glorious Treats
Blintz with Blackberry Sauce from Sommer of A Spicy Perspective
Pastel Rainbow Cake from Bree of Baked Bree
Individual Chocolate Souffles from Andie of Andie Mitchell

pastel rainbow cake

I promise you, if I can make a cake like this, so can you. It just takes a little patience (and a lot of dishes, but it’s worth it for Baby James, right?).

pastel rainbow cake

Pastel Rainbow Cake

Pastel Rainbow Cake

Embellish a cake mix to make a sturdy and moist cake that is perfect for decorating. Vanilla Buttercream tinted beautiful pastels and covered with white chocolate ganache will make one beautiful springy cake perfect for a baby shower.


Vanilla Cake Layers:

  • (I doubled this recipe and baked it into 3 layers, I made a few cupcakes with the extra batter for my kids.)
  • 1 box butter cake mix
  • 1 small box vanilla instant pudding
  • 3 eggs
  • ¾ cup vegetable oil
  • ½ cup water
  • ¾ cup sour cream
  • 2 teaspoons vanilla extract

Vanilla Buttercream:

  • 3 cups (6 sticks) butter, room temperature
  • 6 cups confectioners sugar, sifted
  • 4 teaspoons vanilla extract
  • 1/2 teaspoon salt
  • gel food coloring

White Chocolate Ganache:

  • 1 cup white chocolate chips
  • 1/3 cup heavy cream
  • Edible glitter
  • Yellow sanding sugar
  • Pastel Sixlets


To make the cake layers:

  1. Preheat oven to 350°. Spray (3) 8-inch cake pans with baking spray. (You will have extra batter.)
  2. Add cake mix ingredients to the bowl of an electric mixer. Beat well, about 3 minutes, scraping the bowl occasionally.
  3. Divide batter evenly between cake pans. Bake for 35-40 minutes, or until a toothpick comes out clean. Cool in pans for 10 minutes, turn out and let cool completely on wire racks.

To make the buttercream:

  1. Add the butter to the bowl of a stand mixer. Beat until the butter is pale, very smooth, and makes a slapping sound as it hits the sides of the bowl. This takes about 30 seconds if you butter is really soft, a bit longer if the butter is cooler.
  2. Add the sugar one cup at a time. Mix until it is incorporated before you add the next cup.
  3. When all of the sugar has been added, scrape the paddle and the sides of the bowl. Add the vanilla and salt, beat on low speed for 15 seconds.
  4. Increase the speed to high (or just high enough so that it doesn’t make a mess). Beat until whipped, light, and perfectly smooth, about 5 minutes. Scrape the bowl once or twice. The frosting will look like it is getting really soft, but it will stiffen and increase in volume.
  5. You can use this right away, or store in an airtight container in the fridge for up to one week.

To make the white chocolate ganache:

  1. Bring cream to a simmer on the stove. Pour hot cream over white chocolate. Let sit for 5 minutes. Whisk until completely smooth. (If you have any remaining chunks, you can strain them out.) Let sit for an additional 5 minutes to thicken.

To decorate:

  1. If needed, even cake layers with a serrated knife. Place cake on cake plate, and spread a layer of frosting across the top. Add second layer of cake and repeat. Apply a very thin layer of frosting to the sides and top of cake to seal in crumbs. Let chill for 30 minutes.
  2. Meanwhile, divide the remaining frosting into 6 bowls. Tint with gel food coloring. Using an offset spatula, add colors to the sides of the cake, about an inch up the sides. Be generous, the excess frosting will be removed later. Repeat until you have used all of the colors and the cake is covered. Use a bench scraper to clean edges. (Reserve frosting to use for piping decorations.) Smooth sides and top. Chill for 10 minutes.
  3. Pour thickened ganache over the top of the cake, letting it drip down the sides. Smooth the top with an offset spatula.
  4. Add reserved frosting to a piping bag fitted with a star tip. Sprinkle with sanding sugar and edible glitter. Pipe star shapes on top and add Sixlets for decoration.

Did you make this recipe?

Please leave a comment on the blog or share a photo on Pinterest

pastel rainbow cake

Oh hey there!

Well, hello there! I’m Bree Hester, the Boston-based blogger and food photographer here at Baked Bree. Here you can get lots of weeknight meal inspiration, eat more plant-based meals, and still indulge in a decadent sweet treat. Baked Bree is a place where you will find great recipes and inspiration for your next family adventure.

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This Post Has 29 Comments

  1. bridget {bake at 350}

    Wow, wow, wow, wow, WOW! This cake is gorgeous!

    1. bakedbree

      Thank you Bridget! (That means a lot coming from you!)

  2. Brenda @ a farmgirl's dabbles

    This cake is absolutely beautiful, so perfect for spring! Thank you for joining in on the baby celebration!!

    1. bakedbree

      Thank you Brenda, and thanks for having me!

  3. Meseidy

    You pastry people and your skills! I am always so impressed! Beautiful cake and perfect to celebrate a spring baby!

    1. bakedbree

      Thank you so much! It was fun to make.

  4. JulieD

    Love this cake, Bree!! And the video…so great to see how you made the rainbow gradient…looks so easy!

    Thank you for joining in on the baby shower for Joanne!! xoxo (Hope Pippa is continuing to heal!)

    1. bakedbree

      Thank you! It was really fun to make, video is hard but I love it. And thank you for having me. (She’s so much better, thanks for asking!)

  5. Kathy Strahs

    What a delightfully beautiful cake, Bree!

    1. bakedbree

      Thank you Kathy!

  6. Dev M

    I absolutely adore this cake, and your accompanying video! Sooooo freaking cute!! I can’t even stand it!! Which is why I’m sitting down right now! LOVE it!!

    Your video just may give me the shove I need to start learning some cake decorating basics myself!. Thanks, Bree!

    1. bakedbree

      Thanks Dev! It was really a lot of fun. I think that there are a few tools that really help. I think I need to write a post about that.

      1. Dev M

        Please do, Bree!! ASAP! Haha. I hope you enjoyed your Easter with your family! My brother’s birthday was on Easter this year, so I baked a him a big & tall gingerbread (his favorite) as his birthday cake, which we all loved.

        Can pretty much any cake mix be embellished in this way to make a nice layer cake? Just using different flavors of the pudding mix, I suppose?

        1. bakedbree

          Yes it can, it works like a charm.

  7. Joanne @ Fifteen Spatulas

    Bree!!!!! I’m not even joking when I say that this is the PRETTIEST CAKE I have ever seen. If one made a “Joanne cake” it would look like this. I’m also not one who typically makes magical artwork cakes like this, but your video is awesome. I will absolutely make this for my next special occasion, it’s so beautiful!!

    Thank you for celebrating James, me, and Pete during such a special time. It has been so exciting to start our family and I’ve already been so inspired by you, Wes, Will, Ava, and Clay. I see the fun crafts and things you do together and I can’t wait to do those things with James and hopefully more children coming down the line! Thanks for supporting me throughout the years. xoxo!

    1. bakedbree

      I’m so glad that you like it. I had so much fun making it. That is the sweetest thing to say. I love my little family and being their mom is the greatest gift. Enjoy James, it goes by quickly, but it is worth everything. xoxo.

  8. Sharon @ What The Fork Food Blog

    What a gorgeous cake – I might have to make something similar for my daughter’s 4th birthday 🙂

    1. bakedbree

      She will LOVE it. It screams little girl.

  9. Sarah

    This cake is adorable! I’m thinking about making it now for my daughters first birthday! I just wanted to say hello as well. Just finished your CM store breakout blogging for photographers and loved it! I’m a Marine wife stationed in Quantico so I was sad to see that you’re not living in Alexandria anymore. Looking forward to following you and hopefully finding my inner chef.

    1. bakedbree

      I am so glad! They retired that and I am thinking about doing an updated version of it.

  10. Woon Gie

    Hi, your cake looks super gorgeous! May I know what is the amount of a box butter cake mix? 500g?

    1. bakedbree

      18.25 oz. (I think.) Cake mixes really only come in one size I thought.

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