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This Lucky Charms cupcake recipe is made with cereal milk batter, stuffed with marshmallow fluff, and topped with rainbow buttercream frosting. If you’re looking for easy St. Patrick’s Day cupcakes or a fun rainbow cupcake recipe for kids, this is the one.
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Pin ItThese Lucky Charms cupcakes are the most fun thing I’ve made in a long time.
I’m a 90s kid through and through, and Lucky Charms were a whole event in our house. The cereal was fine, but the marshmallows? That’s what we were really after. So when I set out to make a St. Patrick’s Day cupcake that was colorful, nostalgic, and actually delicious — Lucky Charms were an obvious yes.
These are soft vanilla cupcakes stuffed with marshmallow fluff and Lucky Charms marshmallows, then piled high with rainbow buttercream frosting and topped with those little charms we all used to pick out of the bowl first. They’re festive, they’re fun, and every single person who tries one gets this big happy smile on their face. That’s the whole point!!
If you love Lucky Charms as much as I do, you also need to try my Lucky Charms Ice Cream and Lucky Charms Rice Krispies Treats!
Why You’ll Love These Lucky Charms Cupcakes
Perfect for St. Patrick’s Day: but honestly great for birthdays, parties, or any Tuesday that needs a little magic
Super soft vanilla cake: made with cake flour for that bakery-style crumb
Gooey marshmallow filling: a marshmallow fluff surprise hidden inside every single one!!
Rainbow frosting that’s easier than it looks: one piping bag trick and it comes out perfectly swirled
Cereal milk batter: soaking Lucky Charms in milk takes the flavor to a whole other level
Lucky Charms Cupcake Ingredients
For the Cupcakes:
Cake flour: Creates a super soft, bakery-style crumb — don’t swap it for all-purpose! Here’s how to measure flour correctly.
Baking powder + salt: For lift and balance.
Unsalted butter, softened: Make sure it’s truly room temperature — cold butter won’t cream properly!
Sugar: Sweetens the batter just right without going overboard.
Egg whites: Keeps the cake light, fluffy, and bright white so those rainbow colors really pop!!
Vanilla extract: Use pure, not imitation — you’ll taste the difference.
Whole milk: Or use cereal milk (see the tip below!) for even more Lucky Charms flavor!!
Marshmallow fluff: The gooey surprise filling inside each cupcake. Store-bought works great or try homemade marshmallow fluff!
Lucky Charms marshmallows: Separate the marshmallows from the oat pieces ahead of time — marshmallows go inside and on top, oat pieces go into the cereal milk.
For the Rainbow Buttercream:
Unsalted butter, softened: Room temperature is key for fluffy, creamy frosting.
Confectioners’ sugar: Sifting keeps the frosting silky smooth — don’t skip it!!
Vanilla extract: Pure vanilla for the cleanest flavor.
Gel food coloring: Pink, blue, green, yellow, and purple
The Cereal Milk Trick (Don’t Skip This!!)
This is the move that takes these cupcakes from good to magic. Instead of plain whole milk in the batter, soak Lucky Charms cereal in milk for 30 minutes, then strain it. The result is sweet, cereal-flavored milk that gives the cupcakes that unmistakable Lucky Charms flavor all the way through.
How to make cereal milk: Pour 1 cup of Lucky Charms into a bowl, add 1 cup of whole milk, stir, and refrigerate for 30 minutes. Strain out the cereal before using. Use in place of regular milk in the batter. That’s it!!
You can also make homemade marshmallows for an extra special touch if you want to go all out.
How to Make Lucky Charm Cupcakes
Step 1: Make the batter Cream the butter and sugar together until light and fluffy, about 3 minutes. Slowly add egg whites and vanilla. Alternate adding the dry ingredients (flour, baking powder, salt) with the cereal milk, beginning and ending with the dry ingredients. Mix until just combined — don’t overmix!
Step 2: Bake Fill cupcake liners ¾ full and bake at 350°F until a toothpick comes out clean. Don’t overbake — pull them out as soon as they’re just set. Let cool completely before filling or frosting.
Step 3: Fill with marshmallow fluff and use a melon baller or small spoon to scoop a small hole in the center of each cupcake — don’t go too deep! Fill with a spoonful of marshmallow fluff and a few Lucky Charms marshmallows. Replace the little cake top over the filling.
Step 4: Make the rainbow frosting Beat butter until creamy (2–3 minutes), then slowly add confectioners’ sugar and vanilla until fluffy. Divide the frosting evenly into 5 bowls and color each with gel food coloring — pink, blue, green, yellow, and purple. Gel coloring gives you vibrant color without changing the frosting texture the way liquid food coloring can.
Step 5: Rainbow swirl Lay a piece of plastic wrap flat. Spoon the colors side by side in a row down the center. Roll it into a log shape, twist the ends, and snip one tip. Drop the frosting log into your piping bag fitted with a large round or star tip. As you pipe, all the colors come out together in a beautiful swirl!!
Step 6: Decorate Pipe frosting onto each cupcake. Add Lucky Charms marshmallows right before serving — they’ll get soft and lose their texture if they sit on the frosting too long.
Tips for the Best Lucky Charms Cupcakes
Use gel food coloring, not liquid. Gel gives you vibrant, true colors with just a tiny amount — liquid can make the frosting too thin and the colors muddy.
Don’t overfill the liners. ¾ full is the sweet spot. Too full and they’ll dome and overflow.
Cereal milk is worth the 30 minutes. It makes such a difference in flavor — don’t skip it if you have time!!
Add the Lucky Charms marshmallows right before serving. They’ll soften and get sticky if they sit on the frosting, so decorate at the last minute for the best look and texture.
Make the cupcakes ahead. Bake them the night before and store unfrosted in an airtight container. Frost and fill the day of. Here’s everything you need to know about how to store cupcakes properly!!
Cake flour makes a difference. It creates a softer, more tender crumb than all-purpose. Check out all the best cake flour recipes if you want to keep baking with it!
Make It a St. Patrick’s Day Party
These cupcakes are so much fun as part of a full St. Patrick’s Day spread!! Set up a little dessert table with these, some easy party desserts, and a dessert charcuterie board filled with green and rainbow treats.
For drinks, my Drunken Leprechaun Irish Whiskey Cocktail is the perfect pairing for adults — it’s a pub-style Jameson cocktail that even people who “don’t like whiskey” always love. Or make a big pitcher of Irish Whiskey Green Tea Punch for the whole crew!! The Jameson Jello Shots are always a party hit too!
FAQs
Yes! A white or vanilla box mix works great here. Use the cereal milk in place of the water called for.
Bake the cupcakes up to 2 days ahead. Fill and frost the day of. Add the Lucky Charms marshmallows right before serving.
Yes — a marshmallow fluff buttercream (just beat fluff into your butter and powdered sugar) is amazing here if you want to skip the rainbow swirl.
Store in an airtight container at room temperature for up to 2 days, or refrigerate for up to 4 days. Let them come to room temp before eating. More tips here: how to store cupcakes.
You’ll need 1 cup of Lucky Charms and 1 cup of whole milk for one batch of cupcakes.
More Cupcake Recipes
If you make these for St. Patrick’s Day, tag me at @sugarandcharm — I love seeing your versions!! 🍀 And if you try them, leave a comment and a star rating below. It means so much!
My new Entertaining book is here! Order Now!
Lucky Charms Cupcakes
Ingredients
Vanilla Cupcakes
- 2 1/4 cup cake flour
- 1 tbsp baking powder
- 1/2 tsp salt
- 1 1/4 cup whole milk
- 4 large egg whites
- 2 cups granulated sugar
- 1/2 cup butter, room temperature
- 1 1/2 tsp vanilla extract
- 7 ounces marshmallow fluff
- 1 box Lucky Charms Cereal
Buttercream Frosting
- 2 cups unsalted butter, 4 sticks – room temperature
- 4 cups confectioners sugar
- 3 tsp vanilla extract
- 5 colors food coloring (green, purple, pink, blue and yellow.
Instructions
Vanilla Cupcakes
- Cake flour (2¼ cups): The secret to that soft, bakery-style crumb — don't swap it for all-purpose! Here's how to measure flour correctly.
- Baking powder (1 tbsp) + salt (½ tsp): For lift and just enough balance to keep it from being too sweet.
- Unsalted butter, room temperature (½ cup): Make sure it's truly softened — cold butter won't cream properly!
- Granulated sugar (2 cups): Sweetens the batter just right without going overboard.
- Egg whites (4 large): Keeps the cake light, fluffy, and bright white so those rainbow colors really pop!!
- Vanilla extract (1½ tsp): Use pure, not imitation — you'll taste the difference.
- Whole milk (1¼ cups): Or use cereal milk — soak the Lucky Charms oat pieces in your 1¼ cups of milk for 30 minutes, strain, and use in the batter for that extra Lucky Charms flavor!!
- Marshmallow fluff (7 oz): The gooey surprise filling inside each cupcake. Store-bought works perfectly or try homemade marshmallow fluff!
- Lucky Charms cereal (1 box): Separate the marshmallows from the oat pieces ahead of time — the oat pieces go into the cereal milk, the marshmallows go inside and on top of each cupcake.
Buttercream Frosting
- Unsalted butter, room temperature (2 cups / 4 sticks): Room temperature is essential for fluffy, creamy frosting.
- Confectioners' sugar (4 cups), sifted: Sifting keeps the frosting silky smooth — don't skip it.
- Vanilla extract (3 tsp): Pure vanilla for the cleanest flavor.
- Gel food coloring in green, purple, pink, blue, and yellow (1–2 drops each): Gel only — liquid food coloring makes frosting too thin and colors look dull. Just a tiny drop of gel gives you vibrant, true color!
Notes
- Add Lucky Charms marshmallows right before serving — they’ll get soft if they sit on the frosting too long
- Use gel food coloring only — liquid makes frosting too thin
- Cereal milk tip: soak Lucky Charms oat pieces in milk for 30 min, strain, and use in batter
- Make ahead: bake cupcakes the night before, fill and frost the day of
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
