It was two of Tim’s nieces birthdays over the past month, so his sister had a joint birthday get together for the family this past weekend. I decided to make a little something special for them: rainbow cupcakes!
My friends made me a rainbow birthday cake back in college, and it was super fun and unique! I wanted to make it a little easier… I used boxed white cake mix. Shhh. But hey, you get to make them your own by making a delicious swiss meringue buttercream frosting! It’s super easy and it is DELISH.
I found the frosting recipe on Annie’s Eats. I figured with birthday cupcakes, it would be the perfect time to try such a delicious looking buttercream! I was right. It turned out great. The cupcakes were a huge hit.
Now, don’t be too scared by this frosting, it really is easy to make and it’s so worth it. I found that the original recipe tasted too much like pure butter, so I added about 1 cup of powdered sugar. So you can use your judgment and add it if you want. Also, feel free to use your favorite flavorings instead of vanilla! Like your favorite flavored liquor or maybe some almond extract.
Put this over your favorite cake recipe if you don’t like boxed or don’t want rainbow cupcakes. I also used some pink and purple sprinkles for the girls’ favorite colors. You can omit them or top them with whatever tickles your tastebuds.
Rainbow Cupcakes with Swiss Meringue Buttercream Frosting
(Makes about 18 cupcakes)
For the Cupcakes:
1 box of white cake mix, and the ingredients to prepare it
Neon food coloring (I like the really bright colors it makes!)
For the Buttercream:
5 egg whites
1 c. plus 2 tbsp. granulated sugar
Pinch of salt
1 lb. (4 sticks) unsalted butter, room temperature
2 tsp. of vanilla extract
1 c. of powdered sugar (or enough to your liking), optional
To make the cupcakes…
Preheat the oven according to package directions. Make the cake mix according to package directions.
Grease or line your muffin tin with cupcake liners.
Divide your cupcakes evenly into bowls. I used 4 different colors. Neon green, pink, purple, and blue. There’s a guide on the back of the food coloring box to making different colors. It’s adjusted for a whole package of cake mix, so I used 8 drops for the purple and blue batters, and 10 drops for the pink and green batters. Mix well.
Using a tablespoon from my regular silverware, scoop one tablespoon of color into each cupcake liner. I started with green. Then go around with your second color, third, fourth etc. The colors won’t run together or anything, they stay separated!
Bake according to package directions, or until a toothpick comes out clean. Let cool completely before frosting. Look how rainbow-y they are!
To make the buttercream…
Fill a medium saucepan 1/3-1/2 full of water. Bring to a simmer.
Meanwhile, whisk together the egg whites, sugar and salt in a heatproof bowl. Place the bowl on top of the simmering water. You do NOT want the water to touch the bowl, so make sure that doesn’t happen. Whisk the mixture frequently until it reaches 160 degrees, or until the sugar is dissolved and the whites are nice and glossy.
Place the mixture into a stand mixer bowl and, using the whisk attachment, beat on medium speed until the mixture cools to room temperature and the whites turn into firm, stiff peaks, about 8 minutes.
At this point, add in your butter 2 tablespoons at a time, adding more after each addition. (Tip: Forget to take the butter out of the fridge? Pop in the microwave in the wrapper for about 30 seconds on a low power. Check it about every 10 seconds until it’s just starting to soften!)
Then add in your vanilla extract, and powdered sugar if desired. Mix until just incorporated.
Spread on cooled cupcakes with a knife or pipe on with a ziploc bag with a corner clipped off with or without a pastry tip in.
Sprinkle on toppings if you’d like. Hope you like them!