Rainbow St Patricks Day Cake is super easy to make & the perfect dessert for your St. Patrick’s Day celebrations! Plus it’s topped with MARSHMALLOWS!
Oh my goodness. I’m not a huge cereal fan & we almost never buy it. But one cereal I do really love is Lucky Charms, mostly for the marshmallows.
Yes, I’m a giant child & like to pick them out when I can. So one day my friend shared that she found that you can actually buy just marshmallows. Not the actual Lucky Charm’s brand marshmallows, but similar enough to make me happy.
This post contains some affiliate links. Click here to read my full disclosure policy.
I mean, a whole bag of just marshmallows is pretty exciting for me. So then I was pondering what to make with them. Of course it had to be St. Patrick’s Day related which of course made me think of rainbows.
Which is how this super fun rainbow cake came about. It’s super easy to make too – check it out below!
Rainbow Cake
So really important to remember – do not mix the colors or you will not have pretty definition between them. You will get a big, brownish-green mess.
So I started by spreading the red batter to cover the bottom then drizzling the other colors in layers in alternating directions. That’s it & with just one cake mix- it’s so stinkin’ easy too.
No one has to know it was easy – they will just WOW through every bite.
Here are some commonly asked questions
What is the best way to store leftover Rainbow St. Patrick’s Day Cake?
Be sure to cover tightly or place the cake in an airtight container and keep refrigerated for up to 4 days.
What can I make with rainbow sprinkles?
- St. Patrick’s Day Hot Chocolate Bombs
- Funfetti Cake Batter Dip
- Edible Sugar Cookie Dough
- Frozen Bananas
- Lofthouse Sugar Cookies
- Cake Batter Frosting
- Birthday Sugar Cookie Bars
- Homemade Funfetti Cake
- Rainbow Cake
Can this rainbow cake be frozen?
Yes, I do it often. I like to wait to add the marshmallows until serving when I plan on freezing the cake because the texture of them will change slightly after they have been exposed to the moisture of the refrigerator or freezer.
HOW DO YOU MAKE Rainbow Cake?
- Preheat the oven according to the box mix directions.
- Spray a 9×13 metal baking pan with cooking spray – set aside.
- In a mixer bowl, combine the box mix ingredients & beat until combined.
- Ladle out equal portions of batter into 6 separate bowls.
- Mix in several drops of food color – one for each bowl so you have a rainbow of batter.
- Carefully drizzle the batter into the prepared pan. (I started with red & spread it out to cover the bottom of the pan) Then follow with orange – drizzling on in a random pattern – do not stir or mix – just let them sit on top of each other.
- Follow with remaining colors – yellow, green, blue, purple.
- Bake according to the package instructions – remove & cool completely before adding the frosting.
- Once cool, spread on the frosting, add marshmallows & sprinkles.
Products I love when making this rainbow cake…
This rainbow cake recipe is SUPER EASY and delicious – and if you’re like me this time of year, then you maybe already have some of these items on hand OR maybe you have never made a homemade cake before, & you might be a bit nervous – but you’re going to love it. I have made a list below of the things I absolutely can’t live without when it comes to making this cake recipe.
- White Cake Mix
- 9×13 baking pan
- Red food coloring
- Orange food coloring
- Yellow food coloring
- Green food coloring
- Blue food coloring
- Purple food coloring
- Frosting
- Rainbow sprinkles
- Cereal Marshmallows
St. Patrick’s Day Cake
What are the best sprinkles for this cake?
This is important – just because the package says “sprinkles” doesn’t necessarily mean that it is in-fact sprinkles.
I see a lot of people using colored sanding sugar that is labled as sprinkles.
This will not work as well because when that sugar gets wet – like when mixed into a moist dough or frosting or cake or when it are placed in the refrigerator, it will sweat & the color will bleed out.
Isn’t this just the cutest cake ever?? So easy & perfect for your St. Patty’s Day!!!
If you love this Easy Rainbow St Patricks Day Cake recipe, you’re going to love these other treats too. Please click each link below to find the easy, printable recipe!
If you love this recipe for Rainbow St Patricks Day Cake as much as I do, please write a five-star review, and be sure to help me share on Facebook and Pinterest!
CONNECT WITH YUMMI HAUS!
Be sure to follow me on my social media, so you never miss a post!
Rainbow St. Patrick’s Day Cake
Ingredients
- 1 white cake mix – plus ingredients per the box instructions- oil, water, eggs)
- Food Color red, orange, yellow, green, blue & purple
- 1 can pre-packaged frosting or homemade if you prefer
- Lucky Charm marshmallows – just the marshmallows not the cereal
- rainbow sprinkles
Instructions
- Preheat the oven according to the box mix directions.
- Spray a 9×13 metal baking pan with cooking spray – set aside.
- In a mixer bowl, combine the box mix ingredients & beat until combined.
- Ladle out equal portions of the batter into 6 separate bowls.
- Mix in several drops of food color – one for each bowl so you have a rainbow of batter.
- Carefully drizzle batter into the prepared pan. I started with red & spread it out to cover the bottom of the pan. Then follow with orange – drizzling in a random pattern – do not stir or mix – just let them sit on top of each other. Follow with the remaining colors – yellow, green, blue, purple.
- Bake according to the package instructions – remove & cool completely before adding the frosting.
- Once cool, spread on the frosting, add the marshmallows & sprinkles.
Nutritional information for the recipe is provided as a courtesy and is approximate. Please double-check with your own dietary calculator for the best accuracy. We at Yummi Haus cannot guarantee the accuracy of the nutritional information given for any recipe on this site.
Tamar says
That is amazing!!! How fun!
Molly says
oh my that rainbow cake is amazing
Mollyx
Leslie says
LOVE the swirled effect that crisscrossing the batter makes! And don’t tell my kids they sell just the marshmallows, because they will be begging me for those right up until St. Patrick’s Day!