Colorful DIY Rainbow Desserts

How to make a Rainbow Cake + other Desserts

Celebrating a birthday with a colorful rainbow party? Try baking some delicious and adorable rainbow desserts. From sweet sugar cookies to a colorful rainbow cake, these colorful party treats are perfect for a bright and bold birthday party. Check out all the sugary goodness…

Baking with color has to be the best. Yes…it’s fun to make cute character cookies or to design a fun muted pink floral cake, but using bright and playful colors just makes the heart happy.

Throwing a RAINBOW THEMED PARTY?

☑️ This Rainbow Party Kit is the perfect set to get your party planning headed in the right direction!

For this colorful tween spa party, I made cute rainbow sugar cookies, strawberry cupcakes with colorful fondant toppers and a colorful rainbow layer cake.

How to use Rainbow Cookies, Cakes and Cupcakes

Using rainbow desserts in a party is super easy. Because the treats themselves are colorful, they work really well displayed on white plates and platters.

This simple white cake stand is perfect for this colorful, yet understated cake.

Ideas for a Rainbow party

These rainbow desserts were made for my tween daughter’s recent spa party. We wanted a bright colorful design with a rainbow feel without being strictly rainbow. The design used less common versions of the colors and simple designs.

Rainbow Cookies Tutorial: STEP by STEP

Alright…let’s talk cookies. For the rainbow cookies, I used two different designs. With the first, they cookies were letter cut outs. I used the letter cookies to spell out my daughter’s name on the dessert table.

I then also as favors “tags” for the favor bags. Each girl had a different colored bag of goodies and I matched the cookie color to the bag to help identify who each bag belonged to.

The second design matched the printables I made for the party. I was a series of stripes (kind of like they were made with a paint brush) on a bright white background. Simple and with enough pop of color that it worked perfectly.

Let’s break down how to make these cookies.

Materials:

Square Cookie Cutters
Letter Cookie Cutters
White Fondant (or Red Fondant, Pink Fondant, Teal Fondant, Yellow Fondant, Light Green Fondant and Light Blue Fondant)
Gel Food Coloring (if using White Fondant)
Sugar Cookie Recipe: I used my no-fail, easy to use Sugar Cookie Recipe.
White frosting

Step 1:

First, cut and bake the cookies.

For the sugar cookies themselves, you can use any recipe. I highly recommend my basic cut out sugar recipe. It is really great for keeping shape and it tastes delicious.

Prep the dough according to the recipe.

You will want to use a liberal amount of flour on the surface you are cutting and even a little extra in the dough itself.

Roll out dough until it about ¼ inch thick. Allow the cookie to be a little on the thicker side for even better flavor and shape.

For letter cookies, cut using the letter cutter of your choice. For the rainbow cookies, cut using the small to medium square cookie cutter.

Allow cookies to completely cool prior to decorating. I like to bake the cookies the day before so they are nice a cool for decorating.

Step 2:

Next, you will want to prep your fondant. If you are using white fondant, you will want to color the fondant with the gel food coloring.

If you are using pre-colored fondant, you don’t need to mix any food coloring. Either method works. The only difference is the white fondant option is a little more time consuming, but also more budget friendly.

To color fondant, start with white and add drops of gel food coloring, mixing as you go until fondant is the desired color. Keep mixing until it no longer has a “tie-dyed” look to it. You will need small amounts of red, pink, teal, light blue, green and yellow fondant for this rainbow design.

You will also need larger amounts of the colors you use for the letters.

Step 3:

For the letter cookies: Using your chosen color, roll it out to 1/8 inch thick. Cut the fondant using the same cutter for the letter you baked with. Set aside to begin the drying process. You made need to flip the fondant upside down after an hour or two to allow both sides to evenly dry.

For the rainbow stripe cookies: Roll out white fondant to 1/8 inch thick. Using the same size square cutter you cut the cookie with, cut out a white square. Set aside to dry.

With each color, you will need one “stripe” per cookie. Roll the color out to 1/8 inch thick. Using a knife, cut the fondant into thin strips (approximately 1/8 inch). Cut the strips into pieces ranging from 1/2 inch to an inch long. Set aside to dry.

You want the pieces to be slightly varying lengths to give the cookies the less uniform look.

Step 4:

Once all the pieces are dry, you will gently place the stripes onto the white fondant. I put a very, very small bit of white frosting on the back of each stripe to help it adhere to the white fondant. If the backs of the stripes are still slightly tacky, you can skip the frosting, but it does help keep the pieces secure.

Put a very thin layer of frosting on the cookies and add the fondant toppers. Easy peasy and done!

Rainbow Cake Tutorial: STEP by STEP

And now onto the simple Rainbow cake. This cake was fun to make and delicious! This tutorial will focus on the outside of the cake. For detailed instructions on how to make the rainbow layer cake interior, checkout this layer cake recipe and tutorial first. Then come back for the decorations here!

Materials:

Cake (instructions here)
White frosting (homemade or store bought)
White Fondant (or Red Fondant, Pink Fondant, Teal Fondant, Yellow Fondant, Light Green Fondant and Light Blue Fondant)
Gel Food Coloring (if using White Fondant)
Cake Decorating Tools (optional)

Step 1:

Bake your cake according to recipe. Once the layers are assembled and it’s ready to be frosted, we are ready to start decorating.

Step 2:

For details on prepping fondant, see the cookie instructions above.

Roll out colored fondant to 1/8 thick.

With each color, you will need several “stripes”. Using a knife, cut the fondant into strips (approximately 1/2 inch). Cut the strips into pieces ranging from 1 inch to 2 inch long. Set aside to dry.

You want the pieces to be slightly varying lengths to give the cookies the less uniform look.

Step 3:

For this cake I used a rough ice method. You can also smooth ice it for the same effect. Rough ice is just a little more forgiving. Using a frosting spatula, smooth white frosting over the cake until completely covered and at the desired level of thickness and smoothness.

Gently place rainbow stripes into the frosting along the bottom of the cake.

Add a fun cake topper like this one for an extra special look.

Here is the interior of this fun layer cake…

Rainbow Cupcakes Tutorial: STEP by STEP

Let’s look at how to make these simple fondant cupcake toppers. For these cupcakes, I made my super delicious strawberry cupcakes.

Materials:

Circle Cookie Cutters
White Fondant (or Red Fondant, Pink Fondant, Teal Fondant, Yellow Fondant, Light Green Fondant and Light Blue Fondant)
Gel Food Coloring (if using White Fondant)
White frosting

Step 1:

For details on prepping fondant, see the cookie instructions above.

Roll out white fondant to 1/8 inch thick. Using a 2 inch circle cutter, cut out a white circle. Set aside to dry.

With each color, you will need one “stripe” per topper. Roll the color out to 1/8 inch thick. Using a knife, cut the fondant into thin strips (approximately 1/8 inch). Cut the strips into pieces ranging from 1/3 inch to a 1/2 long. Set aside to dry.

You want the pieces to be slightly varying lengths to give the cookies the less uniform look.

Step 2:

Easy peasy and ready to add to the top of your beautifully frosted cupcakes!

Looking for more ideas for Rainbow Desserts?

Are you looking for more ideas for rainbow themed desserts and treats? Check out these Rainbow Desserts for more inspiration!

Coordinating Rainbow Party Supplies

Serving up fun Rainbow treats is made so much easier with some adorable coordinating tableware! These treats were even made to match these fun options!

Happy Day Partyware from Oriental Trading

Hip Hip Hooray Partyware from Oriental Trading

Rainbow Plates from Amazon

Hip Hip Hooray Plates from Shop Sweet Lulu

Shop This Party

If you would like to shop the party featured in this post, here are the direct links for purchase:

Hip Hip Hooray Rainbow Printables

For this fun rainbow party, I used these simple and colorful printables. With bright white and a rainbow feel, these are so much fun and perfect for a big kid birthday bash:

Here are some helpful links for planning a rainbow party:

Conclusion for Easy DIY Rainbow Cookies + Cake:

If you love rainbows and sugar, these simple and delicious treats are just for you. This post walks you through baking and decorating fun rainbow inspired cookies, cupcakes and a rainbow layer cake! It’s a beautiful day for some rainbow desserts!

If you love these desserts, please pin this image to your birthday Pinterest board: