Key Lime Pie Sheet Cake with Creamy Lime Frosting

Name: Key Lime Pie Cake
Prep time: 15 min
Cook time: 25 min
Total time: 40 min
Yield: 12
Ingredients: 1 box lemon cake mix; 1 cup water; 1/2 cup canola oil; 3 eggs; neon green gel food coloring, few drops; lime, half; juiced; lime, whole; zested; 1/4 cup Graham cracker crumbs; 1/4 cup butter, softened; 4 ounces cream cheese, softened; 2 cups powdered sugar; 1 teaspoon vanilla extract; 1 Tablespoon lime juice; lime, whole; zested; 1-2 Tablespoons milk

By:

Josie Baker

Published:

October 6, 2026

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Key Lime Pie Sheet Cake

This tangy and delicious Key Lime Pie Sheet Cake is a must try for anyone who loves classic key lime pie. The cake is made with real lime juice and lime zest, so every bite carries that bright, zippy flavor we all know and love. On top, you get creamy lime frosting and a generous shower of graham cracker crumbles.

I brought this cake to a neighborhood cookout last summer and watched it vanish before the burgers even came off the grill. My youngest asked if we could make it every single weekend, which is about the highest praise a dessert can get around here.

What makes it so lovable is the balance. The crumb is fluffy and light, the frosting is creamy and rich, and the lime keeps the whole thing tasting fresh instead of heavy. Real limes go into both the cake and the frosting, so that tangy flavor runs through every layer, not just the top.

It is sweet and sour in the best possible way, and it makes a wonderful summer dessert that pleases a crowd. Sheet cakes are also wonderfully low stress. You bake in one pan, frost the top, and serve straight from the dish. No layering, no fussy decorating, no stress.

More Key Lime Treats:

If this cake wins you over, there are two more key lime treats worth adding to your list: Key Lime Cupcakes and a Key Lime Poke Cake recipe. Both keep that same tangy lime flavor in an easy, shareable format.

Cupcakes are perfect for birthdays and classroom parties, while a poke cake is a great pick when you want something extra moist for a potluck.

What You need to Make Key Lime Pie Cake

Here is the full lineup of what goes into this cake. Nothing here is hard to find, and most of it is probably in your kitchen already.

For the cake:

One box of lemon cake mix
1 cup water
1/2 cup canola oil (vegetable oil works just as well)
3 eggs
A few drops of neon green gel food coloring
The juice of half a lime
The zest of one whole lime
1/4 cup graham cracker crumbs

For the frosting:

1/4 cup softened butter
4 ounces softened cream cheese
2 cups powdered sugar
1 teaspoon vanilla extract
1 Tablespoon lime juice
The zest of one whole lime
1 to 2 Tablespoons milk

Kitchen supplies: a 9×13 baking pan, a stand mixer, mixing bowls, and if you want pretty dollops of frosting, a large piping bag with a star tip.

Key Lime Pie Sheet Cake, What You need to Make Key Lime Pie Cake

A quick word on the food coloring. Gel coloring is the way to go here. A few drops give you a vibrant green without thinning out the batter the way liquid coloring can. Start small, stir, and add more until you get the shade you like.

A quick word on the limes. Persian limes are the big, thick skinned, seedless ones you find at most grocery stores. Key limes, also called Mexican limes, are smaller, juicier, have seeds, and can be a touch more acidic.

Either kind works beautifully in this recipe. If you go with key limes, you will need more of them, roughly five key limes for every one large Persian lime.

A quick word on the milk. Any type of milk works in the frosting. Whole milk, 2 percent, skim, almond, and oat all get you a smooth, spreadable frosting. Add it a little at a time until the texture looks right.

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How to Make Key Lime Sheet Cake

Making this cake is genuinely simple. You mix the batter, pour it into the pan, and bake. While the cake cools, you whip up the frosting, spread it over the cooled cake, and finish with graham cracker crumbs. That is the whole game.

Here is the short version, with a few tips I have picked up along the way:

Preheat the oven to 350°F and grease your 9×13 baking pan.
Beat the cake mix, water, oil, eggs, and food coloring together in a medium mixing bowl until everything is well combined.
Add the lime juice and lime zest and mix just until incorporated. Try not to overmix at this stage.
Pour the batter into the prepared pan and bake for 20 to 22 minutes, or until a knife inserted in the center comes out clean.
Let the cake cool completely before you frost it. Warm cake plus creamy frosting equals a slip and slide.
Make the frosting while the cake cools. Cream the softened butter and cream cheese first, then add the powdered sugar, vanilla, lime juice, lime zest, and milk. Beat until smooth.
Spread the frosting evenly over the cooled cake. If you want dollops instead of a flat layer, a piping bag makes it easy.
Crush your graham crackers and sprinkle as much as you like over the top. Thinly sliced limes make a pretty optional garnish.

One more thought on the batter. The lemon cake mix gives you a soft, tender crumb, and the lime juice and zest are what turn it into something that tastes like a key lime pie in cake form. That combination of a bright citrus base with a creamy, tangy frosting is the whole reason this dessert works.

My favorite little trick is to add the graham cracker crumbs right before serving. They stay crisp that way, and that contrast against the creamy frosting is exactly what makes people go back for a second slice. If you are frosting ahead of time, keep the crumb topping in a small bowl and add it at the last minute.

Grab a free printable copy of our Key Lime Pie Cake Recipe:

If you like to keep your recipes on paper, there is a free printable copy of this Key Lime Pie Cake recipe you can save and print for your binder. You are also welcome to rate the recipe and share your own results in the comments, because I read every single one.

A few other recipes you might enjoy: Instant Pot Mango Coconut Bundt Cake, Lemon Blueberry Donuts, Peanut Butter Cup Spider Cookies, Salted Caramel Cookies, and Witch’s Cauldron Brownies.

Ingredients

Here are the exact amounts, separated into the cake and the frosting so you can see the whole picture at a glance.

Key Lime Sheet Cake Ingredients

1 box lemon cake mix
1 cup water
1/2 cup canola oil
3 eggs
A few drops of neon green gel food coloring
Half of a lime, juiced
One whole lime, zested
1/4 cup graham cracker crumbs

Frosting Ingredients

1/4 cup butter, softened
4 ounces cream cheese, softened
2 cups powdered sugar
1 teaspoon vanilla extract
1 Tablespoon lime juice
One whole lime, zested
1 to 2 Tablespoons milk

The graham cracker crumbs are a topping, not a filling, so keep them separate until the very end. If you want a little extra crunch, crush a few more and keep them on the side for people to add at the table.

Instructions

To Make the Cake

Preheat the oven to 350°F and grease a 9×13 baking pan.
Add the lemon cake mix, water, canola oil, eggs, and neon green food coloring to a medium mixing bowl. Beat until well combined.
Add the lime juice and lime zest and mix until incorporated.
Pour the batter into your prepared cake pan and bake for 20 to 22 minutes, or until a knife inserted in the middle of the cake comes out clean.
Remove from the oven and allow the cake to cool.

To Make the Frosting

While the cake cools, make the frosting. First, cream together the softened butter and cream cheese.
Add the powdered sugar, vanilla, lime juice, lime zest, and milk, and beat until smooth.
Frost the cake evenly. Use a piping bag to add dollops if you like.
Sprinkle graham cracker crumbs on top.

A few things I have learned the hard way. Let your butter and cream cheese sit out for about 30 minutes before you start, because room temperature ingredients give you a silky frosting with no lumps.

Add the milk one Tablespoon at a time, since you may not need all of it. If the frosting feels too soft to hold a swirl, pop the bowl in the fridge for 10 minutes and try again.

And if you want the neatest slices, chill the frosted cake for about an hour before cutting.

Store any leftovers covered in the refrigerator, and bring slices to room temperature for a few minutes before serving so the frosting softens back up.

Notes

The nutrition information provided with this recipe is only a rough estimate. Actual values will differ depending on the specific ingredients you use and how much of the recipe you make. Swap in a different cake mix, a different milk, or a lighter frosting, and the numbers will shift again.

Here is the source estimate per serving, based on 12 servings:

Nutrient	Amount
Calories	412 kcal
Carbohydrates	58 g
Protein	4 g
Fat	19 g
Saturated fat	6 g
Fiber	1 g
Sugar	39 g
Sodium	407 mg
Cholesterol	62 mg

Recipe details

Here is the quick rundown so you can plan your baking day.

Detail	Info
Prep time	15 minutes
Cook time	25 minutes
Total time	40 minutes
Servings	12
Course	Dessert
Cuisine	American
Estimated cost	About $6

That makes this an easy dessert to pull together on a weeknight or a busy weekend. One bowl for the cake, one bowl for the frosting, and one pan to bake it all in.

If you are bringing it to a gathering, bake it in the morning and frost it once it has cooled, then add the graham cracker crumbs just before you head out the door.

FAQs

What is key lime pie sheet cake?

Key lime pie sheet cake is a dessert that combines the tangy, sweet flavor of classic key lime pie with the convenience of a sheet cake. It typically features a moist lime-infused cake base, a creamy lime cream cheese frosting, and a graham cracker crumb topping that mimics the pie crust.

What is the difference between key limes and regular limes?

Key limes, also known as Mexican limes, are smaller, more aromatic, and have a thinner rind than regular Persian limes. They are also juicier and tarter, with a higher acidity that gives key lime desserts their signature tang. Regular Persian limes are larger, thicker-skinned, and generally less acidic, making them a common substitute.

How should I store key lime sheet cake?

Keep the cake covered in the refrigerator for up to 3 days because the cream cheese frosting is perishable. For best texture, add the graham cracker crumb topping just before serving to keep it crisp. The un-frosted cake can be frozen for up to 2 months; wrap it tightly in plastic wrap and foil, then thaw overnight in the refrigerator before frosting.

Can I use premade frosting for this key lime cake?

Yes, premade frosting works well as a time-saver. Simply start with one container of store-bought vanilla or white icing and stir in fresh lime juice and lime zest to taste until you reach your desired tangy flavor. This method still gives you a deliciously creamy lime frosting without making it from scratch.

Key Lime Pie Sheet Cake with Creamy Lime Frosting