Rainbow frosting can be intimidating so I am here to help break it down with simple tricks, your ingredients, and tools you need for success! I was ask to bake two separate cakes for a rainbow and unicorn themed birthday party. How could I turn that down? I have never made a rainbow cake but I accepted the job. I was up for the challenge! Let us below start with the basics then get to the good stuff. Here is how to make rainbow buttercream frosting for cakes and cupcakes!
Where to start?
Start with your basic ingredients for a buttercream. You can then began to play with flavors and extracts beyond vanilla!
- Unsalted butter
- Powdered sugar
- Gel coloring
- Milk or heavy whipping cream
- Vanilla extract
These are your ingredients you have to work with. Now, I will say there will be times where you need to double or triple the recipes so you have enough to frost cakes AND enough to pipe these pretty rosettes!
How To Make Buttercream Frosting
We will first cream the softened butter and vanilla extract together. This will help create a smooth texture. Next, we add the powdered sugar and the milk. Powdered sugar is tricky when liquid is involved. We can always add more liquid but you can’t take out. You would have to use more powdered sugar if the mixture gets too thin. Start with 2 tablespoons and then add from there. It is okay to add more sugar and milk if you want more frosting but understand the butter is there to ensure your buttercream is creamy. By adding too much powdered sugar and milk you will increase the chance that your buttercream will harden faster. Which, is fine, you just need to work quickly and be sure to leave the cake out hours before the party. We can get in detail later!
Gel Colors
There are many type of coloring liquids out there, I stick to the gel colors by Betty Crocker. I am trustworthy every time and they are conveniently in stock in the baking aisle in your local grocery store. You can add in as much color as you like. Start small with a few drops and then add as you go until you reach your desire color. The colors range from pastel to neon! So fun! This is one reason I want my buttercream thick for piping, to make sure when I add the gel that the mixture won’t become too liquidity. As you mix the color, the buttercream will loosen up just a bit. After you make your basic buttercream, separate about 1 cup of buttercream into each of the bowls with their individual colors. Mix them and then let’s move to the next step.
Cling Wrap, Large Piping Bag, 1M Tip
For the next steps you will tear off a 15-in (eyeball this) piece of cling wrap. Note: not the cling wrap labeled “press n’ seal.” After that, add about 3 tablespoons of each color in a long line. You will want them close to each other, for the next time. Bring one end of the wrap to meet the other side of the wrap, press to let the air out were the red and purple match up. Fold the met ends back over towards the rolled edge to make a log shape. Add your 1M piping tip to your piping bag and cut the end to expose halfway up the tip. Cut one end of the wrapped frosting then place your wrapped frosting in the piping bag. Twist at the top and pipe away. For the rosettes, you will start at the center and make one loop around the center to create a rose.
Troubleshooting
I made the mistake of adding TOO much of each color frosting on the cling wrap to the point where the wrapped frosting wouldn’t fit comfortably in the piping bag. The frosting, when laying the colors out, should be tight. You will have leftover frosting for another round of piping. Don’t overfill your cling wrap, it will create a mess, I have done the leg work! Watch the video to see how to make rainbow buttercream frosting for cakes! It takes practice and you will get the hang of it! Use this on my favorite strawberry shortbread heart cookies, too!
How To Make Rainbow Buttercream Frosting For Cakes
Ingredients
- 8 sticks unsalted butter
- 4 tablespoons vanilla extract
- 12 cups powdered sugar
- 8 tablespoons milk or heavy whipping cream
- Food colorings
Instructions
- In a large standing mixer, mix 4 sticks butter, 2 tablespoons vanilla extract until creamy on medium speed.
- On low speed, add 6 cups powdered sugar and 4 tablespoons milk. Mix until combined. If you want it thicker, add more powdered sugar. If it becomes too thick, add 1/4 teaspoons milk as needed.
- Frost your cake layers and then add the remaining butter and vanilla extract to the existing frosting. Mix until combined.
- Next, add remaining powder sugar and milk. Blend until combined completely.
- In separate bowls, add colorings of choice. Add 3/4 cup or so to each bowl so you have equal amounts. Then, distribute any leftlover frosting among each bowl. Mix the frostings together one by one.
- Working in two batches, cut off a 15-inch piece of cling wrap. (video is there for visuals) add long lines of colors next to one another. Grab one end of the cling wrap and folder over to the other end of the wrap. Press air out and then drape the folded cling wrap back over the frosting to make a log.
- Prepare your piping bag with the 1M tip, cutting off the plastic tip so the metal piping tip is exposed.
- Cut off one end of the cling wrap and stuff in the piping bag. Pipe away!
