Key Lime Dump Cake Recipe
Bright, tangy, and ridiculously easy, this Key Lime Dump Cake Recipe gives you all the sunshine of a Florida vacation with hardly any effort.
If you love key lime pie but don’t feel like fussing with pie crusts, this might become your new favorite citrus dessert recipe. This key lime dump cake is a one pan dessert that starts with boxed cake mix, gets a boost from real key lime juice and sweetened condensed milk, and finishes with a buttery, golden topping that’s part cobbler, part cake. I make it when the weather warms up, when limes go on sale at the grocery store, or any time I need a “wow” dessert that doesn’t chain me to the kitchen.
You know what? At 50, I’ve done my time with fussy pastries. These days, I want a simple cake recipe that I can pull together while the coffee is brewing, toss in the oven, and still have time to sit on the porch. This key lime dessert hits that sweet spot—big flavor, low stress, and everyone thinks you worked much harder than you actually did.
Why You’ll Love This Key Lime Dump Cake Recipe
- Bright, refreshing flavor that tastes like key lime pie in cake form.
- Super easy dump cake method—no mixer and no fancy skills.
- Uses pantry staples plus fresh or bottled key lime juice for real citrus punch.
- Perfect summer cake recipe for cookouts, potlucks, or pool parties.
- One pan dessert: mix, bake, and serve from the same baking dish.
- Flexible and forgiving—great for beginners or “I don’t really bake” folks.
- Easy to tweak: make it sweeter, more tart, or extra tropical with a few swaps.
- Travels well and serves a crowd, so it’s ideal for holidays and gatherings.
- Cozy enough for winter (when you need a little sunshine) but made for warm weather.
Ingredients
Here’s everything you’ll need for this easy key lime dump cake. I’ll list the basics first, then give a few simple swaps you can use.
For the Key Lime Layer
- 1 can (14 oz) sweetened condensed milk
- 1/2 cup key lime juice (fresh or bottled; Nellie & Joe’s is a solid brand)
- 1 tablespoon lime zest (from key limes or regular limes)
- 1/2 cup sour cream or plain Greek yogurt (use full fat for best creaminess)
For the Cake Layer
- 1 box (15.25 oz) yellow cake mix (white cake mix also works)
- 1/2 cup unsalted butter, melted (1 stick; use real butter, not margarine)
- 1/2 cup coconut milk or whole milk (this keeps the cake tender and moist)
For Topping and Garnish (Optional but Lovely)
- 1/2 cup shredded sweetened coconut (for a tropical dump cake vibe)
- 1/3 cup chopped pecans or walnuts (for crunch)
- Whipped cream or whipped topping, for serving
- Extra lime slices or zest, for garnish
Ingredient Tips
- Key lime juice: Fresh key limes are tiny and a little stubborn to juice. If you don’t feel like wrestling them, bottled key lime juice is perfectly fine. Regular lime juice works too—it’ll be slightly less floral but still delicious.
- Cake mix: Any standard 15–16 oz box of yellow or white cake mix is fine. Store brand is absolutely okay here.
- Butter: I like melted butter in this lime cake recipe because you get even coverage and that buttery “crust” on top.
- Coconut milk: Canned full-fat coconut milk makes this taste like a beach vacation. If you don’t love coconut, just use regular milk.
Directions
This is a classic easy dump cake with just a couple of extra flavor steps. You’re mostly layering and pouring—no whisking egg whites or anything fussy.
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Preheat your oven and prep the pan.
Preheat your oven to 350°F (175°C). Lightly grease a 9×13-inch baking dish with butter or nonstick spray. A glass dish lets you peek at the golden edges. -
Mix the key lime layer.
In a medium bowl, whisk together the sweetened condensed milk, key lime juice, lime zest, and sour cream (or Greek yogurt) until smooth and creamy. The mixture will thicken slightly as the lime juice hits the milk—that’s exactly what you want. -
Spread the lime mixture in the pan.
Pour the key lime mixture into your prepared baking dish and spread it into an even layer. This will be the creamy, tart base of your key lime dessert. -
Add the dry cake mix.
Sprinkle the dry cake mix evenly over the lime layer. Don’t stir. Try to cover all the creamy lime surface so you don’t have dry patches. You can use your clean hands or a spoon to nudge it into the corners. -
Drizzle with butter and milk.
In a small bowl or measuring cup, stir together the melted butter and coconut milk (or regular milk). Slowly pour this mixture over the top of the cake mix, trying to cover as much as you can. You’ll still see some dry spots—that’s okay. Those bits crisp up in the oven. -
Top with coconut and nuts (optional but amazing).
Sprinkle the shredded coconut and chopped nuts over the top. The coconut will toast as the cake bakes and smells like—you guessed it—a tropical vacation. -
Bake until golden and bubbly.
Bake for 35–45 minutes, or until the top is golden brown and the edges are bubbling. Every oven is a little different, so start checking around 35 minutes. The center may still look a bit soft; it will set more as it cools. -
Cool slightly before serving.
Let the cake rest for at least 20–30 minutes. This helps the key lime layer thicken and makes serving easier. Scoop into bowls or cut into squares, and top with whipped cream and a little extra lime zest if you’d like.
If you like a warmer, spoonable dessert, serve at the 20-minute mark. If you want cleaner slices, chill it in the fridge for an hour or two before cutting.
Servings & Timing
- Yield: About 12 servings (more if you cut small squares for a dessert table)
- Prep Time: 10–15 minutes
- Bake Time: 35–45 minutes
- Rest Time: 20–30 minutes
- Total Time: About 1 hour 15 minutes
I often bake this easy dump cake in the morning, let it cool on the counter, then chill it before an evening gathering. The texture gets even better as it sits.
Variations
Once you’ve made this Key Lime Dump Cake Recipe once, it’s fun to play with it a bit.
- Extra Tart: Add an extra 2–3 tablespoons of key lime juice for a sharper, more tangy flavor.
- Cream Cheese Swirl: Drop spoonfuls of softened cream cheese over the lime layer before adding the cake mix and swirl gently with a knife.
- Berry Twist: Scatter 1–1 1/2 cups of fresh raspberries or blueberries over the lime layer for a sweet-tart, colorful dessert.
- Gluten-Free Version: Use your favorite gluten-free yellow or white cake mix and follow the recipe as written.
- No Coconut: Leave out the coconut and use only nuts, or just skip both for a smoother top.
- Key Lime Poke Dump Cake: After baking and cooling, poke holes in the cake and drizzle with a small amount of sweetened condensed milk or lime syrup for extra moisture.
Storage & Reheating
This is one of those one pan desserts that actually tastes better the next day, which makes it great for parties and holidays.
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Refrigerator:
Cover the cooled baking dish tightly with plastic wrap or a lid. Store in the fridge for up to 4 days. The key lime layer stays creamy and the flavors meld nicely. -
Freezer:
For longer storage, cut the cake into squares, place on a parchment-lined tray, and freeze until solid. Then wrap each piece in plastic and place in a freezer bag. Freeze for up to 2 months. -
Reheating:
From the fridge, you can serve the cake chilled (it’s like a firm key lime dessert bar) or warm individual servings in the microwave for 15–20 seconds. From the freezer, thaw overnight in the fridge, then warm gently if you prefer it warm. -
Make-Ahead Tips:
Bake the lime cake recipe the day before your event, let it cool completely, then cover and chill. Just before serving, add fresh whipped cream and lime zest so everything looks bright and fresh.
Notes From My Kitchen
- Sweet vs. tart balance: Everyone’s “just right” for key lime is a little different. My husband likes it mouth-puckering, while my grandkids want it sweeter. Taste the lime mixture before you pour it into the pan; if it’s too tart, add a tablespoon or two of sugar.
- Texture preference: Warm, this tastes like a gooey tropical dump cake. Chilled, it slices like a cross between cobbler and custard. I actually like to serve some warm and keep some chilled for later, because the experience is different and fun both ways.
- Zesting tip: Use a microplane and only grate the bright green part of the peel—the white pith underneath is bitter. It’s a tiny extra step that pays off in flavor.
- Serving for guests: For a prettier presentation, cut chilled squares, plate them, then let them sit at room temperature for 10–15 minutes. Top with a dollop of whipped cream, lime zest, and maybe a little toasted coconut.
- Pan choice: A metal pan will brown a bit faster than glass. If you’re using a dark metal pan, start checking for doneness a few minutes early.
Honestly, this is one of those key lime baking recipes that looks more “fancy” than it is. No one needs to know you started with a boxed mix—unless you want to share the secret.
FAQs
Can I use regular limes instead of key limes?
Yes. Regular limes work very well in this Key Lime Dump Cake Recipe; the flavor will be a little less floral but still bright and delicious.
Do I have to use sour cream or Greek yogurt?
I recommend it because it makes the lime layer creamy and balances the sweetness, but you can skip it if you need to; the filling will just be a bit sweeter and looser.
Why is my dump cake still jiggly in the middle?
A little jiggle is normal when it’s hot; it will set more as it cools. If the top isn’t golden and the edges aren’t bubbling, give it another 5–10 minutes.
Can I make this key lime dessert dairy-free?
You can experiment with dairy-free sweetened condensed milk, coconut cream yogurt, and vegan butter; the texture may change slightly, but the flavors still work nicely.
What’s the best way to serve this at a party?
Bake it in a pretty 9×13 dish, let it cool, and serve it right from the pan with a big spoon and a bowl of whipped cream on the side, or chill and cut into neat squares for a dessert buffet.
Can I reduce the sugar?
Most of the sweetness comes from the sweetened condensed milk and cake mix, so you can’t reduce it much without changing the structure, but you can add extra lime juice and zest for a less sweet, more tangy bite.
Can I double this recipe?
Yes, but instead of stacking layers deeper, bake it in two separate 9×13 pans so it cooks evenly and you still get that nice golden top.
Is this safe to leave out on the counter?
Because of the dairy, treat it like you would cheesecake—leave it out for up to 2 hours when serving, then pop it back in the fridge.
Conclusion
This Key Lime Dump Cake Recipe is my go-to “sunshine on a plate” dessert—bright, creamy, buttery, and so simple that you can throw it together on a busy weeknight or before a summer cookout without breaking a sweat. It’s an easy dump cake that tastes like you fussed over it, with the fresh, zesty flavor of a classic key lime dessert and the comfort of a warm, cozy cake.
If you make this, I’d love to hear how it turned out—tell me in the comments what tweaks you tried, and whether you liked it better warm or chilled. And if you’re in a citrus mood, check out my other recipes like lemon bar cookies and coconut sheet cake for even more bright, sunny sweets.
Key Lime Dump Cake
Ingredients
- 1 can sweetened condensed milk 14 oz
- 1/2 cup key lime juice fresh or bottled
- 1 tablespoon lime zest from key limes or regular limes
- 1/2 cup sour cream or plain Greek yogurt full fat for best creaminess
- 1 box yellow cake mix 15.25 oz; white cake mix also works
- 1/2 cup unsalted butter melted
- 1/2 cup coconut milk or whole milk
- 1/2 cup shredded sweetened coconut optional, for topping
- 1/3 cup chopped pecans or walnuts optional, for topping
- Whipped cream or whipped topping for serving, optional
- Extra lime slices or zest for garnish, optional
Instructions
- Preheat your oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish with butter or nonstick spray.
- In a medium bowl, whisk together the sweetened condensed milk, key lime juice, lime zest, and sour cream or Greek yogurt until smooth and creamy. The mixture will thicken slightly.1 can sweetened condensed milk, 1/2 cup key lime juice, 1 tablespoon lime zest, 1/2 cup sour cream or plain Greek yogurt
- Pour the key lime mixture into the prepared baking dish and spread it into an even layer to form the creamy, tart base.
- Sprinkle the dry cake mix evenly over the lime layer without stirring. Try to cover all of the lime layer, nudging the mix into the corners as needed.1 box yellow cake mix
- In a small bowl or measuring cup, stir together the melted butter and coconut milk or whole milk. Slowly pour this mixture over the cake mix, trying to cover as much as possible. Some dry spots are fine.1/2 cup unsalted butter, 1/2 cup coconut milk or whole milk
- Sprinkle the shredded coconut and chopped nuts evenly over the top, if using.1/2 cup shredded sweetened coconut, 1/3 cup chopped pecans or walnuts
- Bake for 35–45 minutes, or until the top is golden brown and the edges are bubbling. Start checking around 35 minutes. The center may look slightly soft; it will set as it cools.
- Let the cake rest for 20–30 minutes before serving. Scoop into bowls or cut into squares. Serve warm or chilled, topped with whipped cream and extra lime zest or slices if desired.Whipped cream or whipped topping, Extra lime slices or zest
