Key Lime Icebox Cake
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A bite of this luscious key lime icebox cake will instantly transport you to paradise. Creamy key lime custard is layered between graham crackers to make a retro icebox cake that’s perfect for hot summer days.
Beat the heat this summer with this cool and refreshing Key Lime Icebox Cake. It’s a no-fuss, no-bake treat that’s easy to put together, with tropical vibes in every delicious bite. This icebox cake is a throwback vintage dessert that’s perfect for warm summer evenings when the last thing you want to do is turn on the oven.
Crisp graham crackers meld with a tangy key lime custard filling for a treat that’s not too sweet and not too tart. As the cake chills in the freezer, the graham cracker layers soften to a cake-like texture while the tangy flavor of the key limes mellows out in the rich creaminess of the custard.
With just a few simple ingredients and a little prep time, this is going to be a go-to summer dessert for you and your family. You should also try my Banana Icebox Cake or Lemon Icebox Pie to finish off your next cookout!
Let’s get started on this easy layered dessert.
Ingredients
This section includes ingredient notes and substitution options. Get all measurements, ingredients, and instructions in the printable recipe card at the end of this post.
- Granulated Sugar — Provides sweetness for the custard and balances the tart flavor of the key limes.
- Cornstarch — This acts as a thickening agent for the custard.
- Egg Yolks — Thickens the custard, making it perfectly rich and creamy.
- Half and Half — A mixture of whole milk and cream, half & half is also used to make the lime custard.
- Butter — Adds richness to the custard filling. Make sure it’s room temperature so that it’s easier to whisk in with the other ingredients.
- Key Limes — Key limes are small, sweet yet tart, and refreshing. You’ll use both the zest and fresh lime juice from the key limes. If you can’t find them at your local store, regular limes can be used too. You may also want to garnish with fresh lime slices to dress up the dessert before serving.
- Graham Crackers — When they soften between the layers of custard, the crackers become cake-like yet still hold up well. The sweet honey taste of the graham crackers perfectly complements the tart lime flavor.
- Heavy Whipping Cream — This is used to make homemade whipped cream for the top of the cake. Cool Whip or homemade whipped topping could be used as a substitute.
- Confectioners Sugar — aka powdered sugar, it is combined with the heavy cream to make the whipped cream topping.
Equipment Needed
To get started on your key lime pie icebox cake, you’ll need these kitchen tools and supplies:
- whisk
- mixing bowls
- measuring cups and spoons
- 8×8 inch square baking dish
- plastic wrap
- hand mixer or stand mixer with whisk attachment
How to Make Key Lime Icebox Cake
This section shows you how to make the recipe with step-by-step photos and instructions. For the full printable recipe, see the recipe card below.
Steps 1 & 2: Make the custard. Whisk together the egg yolks and half-and-half in a small bowl. In a medium saucepan over medium heat, mix the sugar and cornstarch, then gradually whisk in the egg mixture. Bring to a boil, whisking continuously, then remove from heat and add the butter, lime zest, and freshly squeezed lime juice. Allow to cool for 10 minutes.
Steps 3 – 5: Layer the cake: Cover the bottom of a square baking dish with plastic wrap, leaving it overhanging the sides by a couple of inches. Start with a layer of graham crackers at the bottom of the pan. Spoon a portion of the creamy filling over the crackers, spread evenly, and repeat until all ingredients are used up, ending with a top layer of crackers.
Chill the cake: Cover the icebox cake with plastic wrap and freeze. Leave the cake in the freezer for at least 8 hours or overnight. Turn out the frozen cake onto a serving platter and let it thaw at room temperature for about an hour.
Step 6: Make the whipped topping: Beat the heavy whipping cream and confectioners sugar with an electric mixer on high speed until soft peaks form. Spread the whipped cream over the cake. Optionally, garnish with a lime zest and/or fresh lime slices before serving.
Serving Suggestions
This Key Lime Ice Box Cake is a delicious dessert for a summer barbecue. Serve it alongside a scoop of coconut sorbet or vanilla ice cream to complement its rich key lime flavor.
Storage and Freezing
Fridge: Store in an airtight container or lightly covered with plastic wrap in the refrigerator for up to 3 days.
Freezer: Store in the freezer for up to one month. After assembling the cake, make sure to wrap it tightly with plastic wrap or store it in an airtight container to prevent freezer burn and absorption of other flavors from the freezer.
When you’re ready to serve the cake, allow it to thaw in the refrigerator or at room temperature for an hour, as per the original recipe instructions.
Tips for Making Key Lime Pie Icebox Cake
- When zesting the limes, be careful to only get the green outer layer, not the white pith underneath, which can be bitter.
- Roll limes on the countertop before cutting and juicing them. This helps to break down some of the fibers and release more juice.
- If you want to double the recipe, make it in a 9×13 casserole dish. This is a great way to feed a crowd.
- For neat and even layers, use a spatula or the back of a spoon to spread the custard evenly over the graham crackers.
Additions and Variations
- Swap out the crackers. Instead of graham crackers, use vanilla wafers for a different flavor combination that still pairs well with the lime.
- Go for a different flavor. Substitute key lime zest and juice with lemon juice and zest or orange juice and zest for a different citrusy take on this cake. Lemon Icebox Cake or Orange Icebox Cake can be just as refreshing and delicious.
- Add the taste of coconut. Sprinkle toasted shredded coconut over the top. The tropical flavors of lime and coconut are so delicious together!
Recipe FAQ
An icebox cake is a no-bake dessert made by layering cookies or crackers with whipped cream or custard, then chilling it until the layers meld together. The name originates from the “icebox,” a precursor to the modern refrigerator. This Key Lime Icebox Cake is a variant that features key lime custard and graham cracker layers — the perfect dessert for summer.
You can use them to make other desserts like angel food cake, amaretti cookies, or a lemon raspberry cake.
Yes, you can use regular limes if key limes are not available. The flavor may be slightly different, but it will still be delicious! Regular limes are more tart than key limes, but you’ll deal with fewer seeds and can get more lime zest since the skin is thicker on regular limes.
Yes, freezing the key lime cake helps to firm up the layers and make it easier to slice.
More Icebox Cake Recipes
Is there any easy dessert that’s better than a cool and creamy icebox cake on a sweltering hot day? I don’t think so! You can find even more icebox cakes here:
- Pistachio Icebox Cake — for all the pistachio fans out there. Absolutely delectable.
- Boston Cream Icebox Cake — the richness of an éclair and a Boston Cream pie in a cool and refreshing frozen dessert.
- Strawberry Icebox Cake — just 3 ingredients; it couldn’t be easier.
Key Lime Icebox Cake
Ingredients
- ¾ cup granulated sugar
- ¼ cup cornstarch
- 4 large egg yolks
- 2 cups half-and-half
- 3 Tablespoons butter
- 2 Tablespoons key lime zest
- ½ cup key lime juice
- 15 graham crackers
- 1 cup heavy whipping cream
- ¼ cup confectioners sugar
Instructions
- In a small bowl, whisk together the egg yolks and half-and-half.
- In a medium saucepan, add the sugar and cornstarch and whisk to combine. Turn the heat to medium and whisk the egg mixture slowly into the sugar mixture. Bring to a boil while whisking constantly. Let boil for 1 minute, whisking constantly, then remove from heat.
- Whisk in the butter, lime zest, and lime juice. Set the custard aside to cool for 10 minutes.
- Cover the bottom of an 8-inch square baking dish with plastic wrap, letting it overhang the edges by a couple of inches on both sides.
- Add a single layer of graham crackers to the baking dish, breaking them as needed to cover the bottom. Spoon 1/4 of the custard over the graham crackers and spread into an even layer. Repeat the layers 3 more times ending with a top layer of crackers.
- Cover with plastic wrap and freeze for at least 8 hours (or overnight).
- An hour before serving, remove the cake from the freezer, uncover it, and carefully turn it out onto your serving platter. Let the cake thaw at room temperature for 1 hour.
- While the cake is thawing, prepare the whipped cream. In the bowl of a stand mixer fitted with the whisk attachment or in a large bowl with an electric hand mixer, beat the heavy whipping cream and confectioners sugar until soft peaks form.
- Spread the homemade whipped cream on top of the cake, garnish with a slice of lime and/or lime zest, slice, and serve.
Notes
- Store in an airtight container or tightly covered with plastic wrap in the refrigerator for up to 3 days.
- You can use regular limes instead of key limes if you prefer or if they aren’t available your local grocery store.
Nutrition
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