A fluffy and delicious Lucky Charms Sheet Cake made with cereal milk! The lightly toasted and sweet flavor of Lucky Charms cereal is an unexpected but wonderful surprise in this unique Cereal Milk Cake, topped with a cereal milk-vanilla buttercream and plenty of Lucky Charms marshmallows.

Lucky Charms Cereal Milk Cake Recipe

One of my favorite things to do is to plan special treats and surprises for my family, especially themed treats – whether it’s for a movie night or a holiday like St Patrick’s Day, or just some random made-up occasion.

I wanted to do something with Lucky Charms marshmallows but I didn’t want to play it safe and just add them on top of just green-dyed cupcakes or cake – I really wanted to make something exciting for St Patrick’s Day…

There is this bakery chain called Milk Bar that sells Cereal Milk and Cereal Milk Ice Cream. It’s just regular milk that has been flavored to taste just like the sweet, sugary milk that we would all slurp out of our cereal bowls as kids, and to me, that sounded like a brilliant addition to a Lucky Charms themed cake to bring the cereal theme full-circle.

The result was a tender, fluffy cake that has the lightly toasted and sweet flavor of Lucky Charms cereal balanced with a touch of vanilla, topped with a silky smooth homemade vanilla buttercream and plenty of bright and colorful Lucky Charms marshmallows.

Now, while I made our cake from scratch, you could just make the cereal milk and use that for the liquid called for in a boxed cake mix. You’d still get that fun cereal milk flavor with a bit less effort. Use a white cake mix for best results with the food dye.

— Jennifer

Lucky Charms Sheet Cake Ingredients

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Cake Ingredients:

• Lucky Charms, cereal separated from marshmallows
• Milk
• All-Purpose Flour
• Baking Powder
• Cornstarch
• Salt
• Butter, softened
• Vegetable Oil
• White Sugar
• Eggs, room temperature
• Vanilla Extract
• Green Food Dye, as desired

Frosting Ingredients:

• Butter, softened
• Powdered Icing Sugar
• Cereal Milk*
• Vanilla Extract
• Rainbow Sprinkles, as desired

Scroll down to the printable recipe card for full measurements.

Kitchen Tools You May Find Helpful

• 9 x 13″ baking dish
• Stand Mixer or Electric Hand Mixer
• Cookie Pan
• Fine Mesh Strainer
• Mixing Bowl, Measuring Cups, and Spoons
• Offset Spatula

How to Make Cereal Milk Cake

Preheat oven to 300F.

Spread the Lucky Charms cereal (no marshmallows) onto a lined baking sheet and bake for 15 minutes, stirring halfway. Allow cereal to cool.

Place the cooled cereal and milk in a large bowl and allow to soak for 15 minutes.

Drain and save the milk and discard the cereal.

Preheat oven to 350F.

Line and grease a 9″ x 13″ casserole dish and set aside.

In a small bowl, whisk together the flour, baking powder, cornstarch and salt. Set aside.

In a large bowl, beat together the butter, oil and sugar for 2 minutes until light-colored.

Beat in the eggs, vanilla extract and 3/4 cup of the reserved cereal milk.

Beat in the dry ingredients until just incorporated.

Dye the batter with green food dye, if using, just a bit darker than you want your finished cake to turn out.

Pour the batter into the greased casserole dish and bake for 28-32 minutes, until an inserted toothpick comes out clean.

Allow the cake to cool completely before frosting.

In a large bowl, beat together the butter, 3 cups of the powdered sugar, 2 Tablespoons of the cereal milk and the vanilla extract.

Beat for 2 minutes before adjusting the texture with additional powdered sugar, if needed.

Use an offset spatula to spread the frosting over the cooled cake.

Garnish with Lucky Charms marshmallows and sprinkles.

Lucky Charms Cereal Milk Cake FAQ

How do you make cereal milk? We skipped the brown sugar and salt called for in the Milk Bar version and just stuck to two ingredients: cereal and milk. We toasted the cereal in the oven for 15 minutes and then soaked it in milk to infuse the milk with the cereal flavor. After soaking for 15 minutes, we strained the cereal out of the milk, discarded the cereal and then proceeded to use the cereal milk flavored-milk to make our cake. (Step-by-step directions are included in the recipe card below.)

Do I need to bake the cereal before making the cereal milk? Yes, for two reasons: baking the cereal makes it a bit harder so it doesn’t completely disintegrate while being soaked in the milk; and two, because baking the cereal lightly toasts it and makes the cereal’s flavor more intense.

Grab your free printable recipe card for our Lucky Charms Sheet Cake recipe:

Pin this Lucky Charms Sheet Cake for a unique and tasty St Patrick’s Day dessert:

You might also like our Irish Soda Bread recipe or our Lucky Charms Cupcake recipe: