Celebrate Spring by Making Rainbow Frosted Lemon and Lime Cupcakes

Add some color and fun to your day with these lemon and lime flavored rainbow frosted cupcakes!


This week, I was ready to celebrate St. Patrick’s Day, but also so, so ready for winter to be OVER!  The extra hour of daylight we gained this week has me craving spring and sunshine.  This inspired me to bake cupcakes with the bright flavor of fresh lemon and lime.  I added in a little green food coloring, then decorated them using a super easy rainbow frosting method, and topped them off with gold glitter sprinkles.  These cupcakes are sure to make any big or little leprechaun happy or steal them for a fun birthday celebration!

This was my first attempt at making swiss meringue buttercream frosting.  I wanted the frosting to be more tart and lemony rather than super sweet.  For those of you who haven’t tried it, swiss buttercream has a richer, more buttery flavor than traditional buttercream without as much sweetness.  It sounds a little intimidating to make since it involves egg whites and temperature measuring, but don’t be afraid- just dive in! For me, part of the fun was trying something new.  It’s only frosting and even if it isn’t perfect it’s still usually pretty tasty!

Rainbow Frosted Cupcakes

(makes 15 cupcakes)


(*adapted from Makebakecelebrate.com)

  • 1/3 cup salted butter
  • 3/4 cup sugar
  • 1/3 cup sour cream
  • 3 egg whites
  • 1 1/2 cups all purpose flour
  • 1/2 tbsp baking powder
  • 1 tbsp fresh lime juice
  • 1/4 cup skim milk
  • zest of 1 lime
  • Optional- food coloring
  1. Preheat the oven at 350.  Add the dry ingredients together and mix.
  2.  In separate bowl, cream butter and sugar until fluffy.
  3. Add sour cream.  Beat until combined.
  4. Add slightly beaten egg whites in one at a time.
  5. Add lime zest
  6.  Slowly add dry ingredients and beat until combined.
  7. Add milk, lime juice, and a few drops of food coloring if desired (I used green for St. Patrick’s Day).  Beat 30 seconds.
  8.  Fill cupcake liners 1/2-2/3 full.  (Don’t fill over 2/3 or they wil leak over the edge…trust me!)
  9. Bake 15-16 minutes or until they are cooked through.  Cool completely before frosting.

Rainbow Frosting

  • 1 1/4 cup sugar
  • 3 large egg whites
  • 1/8 tsp salt (I did not add since I used salted butter)
  • 4 sticks of butter
  • Fresh squeezed lemon juice to taste (I used the juice of 3 lemons)

You will also need food coloring in all the colors of the rainbow (ROYGBIV!).

(How to decorate cupcakes with rainbow frosting video coming soon!!)

I used King Arthur Flour’s Swiss Buttercream recipe and flavored it with lemon juice.  It made enough to frost all 15 cupcakes.

I did find that it took a LONG time for the egg whites to heat up.  Part of this might have been because I was impatient and did not let the pan of water get to a simmer before I placed my egg whites over it.  Definitely make sure you heat it up the egg whites all the way to 160 degrees per there instructions.  My frosting was slightly gritty because I did not heat it enough to quiet dissolve all the sugar.  It still tasted amazing, but avoid my mistake and you should have both tasty AND smooth frosting.

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