St. Patrick’s Day Cake

It’s mid-March, and the buzz of St. Patrick’s Day is in the air—green everywhere, a hint of mischief, and that itch to bake something special. I remember last year, standing in my kitchen with a wild idea: a cake that captures the luck of the Irish in every bite. That’s when St. Patrick’s Day Cake came to life—a towering, rainbow-layered beauty stuffed with Lucky Charms and topped with a leprechaun-hat vibe. It’s a showstopper that looks like hours of work but preps in just 20 minutes, perfect for 2025’s craze for easy holiday baking. My friends still talk about that first slice—moist, colorful, and pure fun. Let’s dive into this festive tale together, step by step, with every detail to make your St. Patrick’s Day Cake the star of the celebration.

Must-Have Kitchen Tools

Before we start, let’s round up the gear. You don’t need a pot of gold to bake St. Patrick’s Day Cake, but a few tools make it a snap. You’ll want an 8-inch cake pan and five 6-inch cake pans—this set has both sizes and is nonstick heaven, grab it here. A handheld mixer is key for that fluffy batter—this one is my trusty sidekick. And a piping bag with a medium round tip nails the buckle—this kit is affordable and versatile. Disclosure: This post contains affiliate links, meaning I may earn a small commission if you purchase through them, at no extra cost to you. With these ready, you’re set to bake a rainbow.

Ingredients

Here’s what you’ll need for St. Patrick’s Day Cake (serves 12-15):
For the Cake:

• Cooking spray
• 5 ½ cups (660 g.) all-purpose flour
• 1 Tbsp. baking powder
• 1 tsp. kosher salt
• 3 cups (600 g.) granulated sugar
• 1 cup (2 sticks) unsalted butter, softened
• 1 cup vegetable oil
• 6 large eggs
• 1 Tbsp. pure vanilla extract
• 1 cup whole milk
• 1 cup sour cream
• Red, orange, yellow, green, blue, and purple food coloring

For the Frosting & Assembly:

• 8 cups (920 g.) powdered sugar
• 2 ½ cups (5 sticks) unsalted butter, softened
• ⅓ cup heavy cream
• 2 tsp. pure vanilla extract
• ¼ tsp. kosher salt
• 1 ½ cups Lucky Charms marshmallows
• Green, black, and yellow food coloring

These ingredients are your rainbow palette—simple staples turned into festive rainbow desserts with a playful twist.

Step-by-Step Instructions

Let’s bake this lucky masterpiece, with every step laid out.

Step 1: Prep the Pans and Oven
Preheat your oven to 350°F. Line one 8-inch cake pan and five 6-inch pans with parchment, then coat with cooking spray—don’t skimp, or you’ll be prying cake later. This sets the stage for your St. Patrick’s Day Cake.

Step 2: Mix the Dry Ingredients
In a large bowl, whisk the flour, baking powder, and salt until they’re best friends—no clumps allowed. This is the backbone of your cake, so give it a good stir.

Step 3: Cream the Wet Base
In another large bowl, use your handheld mixer on medium-high to beat the granulated sugar and butter until combined—about a minute. Add the oil and keep beating until it’s smooth and creamy, like a dreamy cloud. Add the eggs one at a time, beating well after each, then mix in the vanilla. This mix is the heart of your easy holiday baking adventure.

Step 4: Combine Wet and Dry
Add a third of the dry mix to the wet, beating on medium-low until just a few streaks remain. Pour in the milk and beat until it’s smooth. Add another third of the dry mix, beat again, then add the sour cream and mix well. Finish with the last of the dry ingredients, beating until just combined—don’t overdo it, or the cake gets dense.

Step 5: Color the Batter
Divide the batter evenly into six bowls. Dye one red, one orange, one yellow, one green, one blue, and one purple—use a few drops of food coloring and stir until vibrant. This is where St. Patrick’s Day Cake turns into a festive rainbow dessert.

Step 6: Bake the Layers
Pour the purple batter into the 8-inch pan and bake for 15-18 minutes, until a tester comes out clean. Let it cool. Pour the other colors into the 6-inch pans and bake for 30-35 minutes, testing for doneness. Let them cool too. You’ve got your rainbow stack ready.

Step 7: Make the Frosting
In a large bowl, beat the powdered sugar and butter on medium speed until smooth. Add the heavy cream, vanilla, and salt, beating until fluffy—this buttercream is your canvas.

Step 8: Assemble the Cake
Trim the cake tops if they’re domed. Use a 3-inch cookie cutter to cut centers from the orange, yellow, green, and blue layers. Stack the purple layer on a stand, frost the top lightly, then add the blue, green, yellow, and orange layers, frosting between each. Fill the center with Lucky Charms marshmallows, then top with the red layer. Frost the whole cake thinly for a crumb coat and chill for 30 minutes to 2 hours.

Step 9: Decorate Like a Leprechaun
Dye most of the remaining frosting green and frost the cake smoothly with an offset spatula. Scoop out 1 ½ cups of frosting—dye 1 cup black and ½ cup yellow. Frost a 1-inch black belt near the base (use parchment to keep lines clean), then pipe a yellow buckle with your piping bag. Your St. Patrick’s Day Cake is now a leprechaun hat!

Tips for the Best St. Patrick’s Day Cake

Here’s how to make it shine, from my trial and error:

• Color Pop: Gel food coloring gives bolder hues than liquid—perfect for festive rainbow desserts.
• Time Saver: Bake layers a day ahead, wrap, and chill—cuts morning stress.
• Frosting Fix: If it’s too soft, chill it 10 minutes before piping.
• Kid Fun: Let little ones add the marshmallows—they’ll love it.

That last one came from my nephew’s glee last year—he turned the filling into a game, and it made the cake even more special.

Nutritional Info

Per slice (based on 15 servings):

• Calories: ~800 (varies with frosting)
• Protein: 8g
• Fat: 45g
• Carbs: 100g
• Sugar: 75g
• Sodium: 350mg

It’s a celebration treat—rich, but worth it for easy holiday baking.

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FAQs

Answers from my kitchen adventures:

Can I use one pan size?
Yes, use six 8-inch pans—just adjust bake times and skip cutting centers.

No Lucky Charms?
Swap with sprinkles or mini marshmallows—still festive.

Can I freeze it?
Freeze layers for 2 weeks; frost fresh for best texture.

Why’s my frosting runny?
Add more powdered sugar or chill it—humidity’s the culprit.

Conclusion

St. Patrick’s Day Cake is pure joy—a rainbow of flavor and fun that fits 2025’s love for easy holiday baking. Whether it’s a party centerpiece or a family treat, it’s a festive rainbow dessert that’s simple yet dazzling. Grab your pans (like this set), bake it up, and spread the luck. Pin your masterpiece or drop a note—I’d love to see it! Want more festive rainbow desserts? Follow my Pinterest for holiday baking that’s always a hit.