Key Lime Butter Cake

4.25 from 4 votes

An EASY Key Lime Butter Cake is a cake that explodes with lime flavor. The cake is soaked with lime syrup and the whole thing is topped with key lime drizzle – this cake screams key lime dessert! Thanks to my partnership with Challenge Dairy, this cake is an explosion of buttery lime flavor.

If there is one thing I cannot resist, it’s a lemon or lime dessert. It took every single ounce of willpower I had to just taste a bite and freeze this cake for Easter. But I still know it’s there…


key lime bundt cake on cake stand

Remember my Lemon Butter Cake? Well, this recipe is that cake with a key lime makeover! I’ve had nothing but good reviews about that cake, so I decided it was time to soak it in another flavor that’s popular right now: KEY LIME. Maybe you’re thinking Key Lime in a butter cake? But trust me, this cake is amazingly good and will be a huge hit. If you’re looking for a new key lime dessert, this is it!

You may be asking yourself: what’s a butter cake? Is a butter cake the same as a gooey butter cake? (Short answer: no.) Basically, in my world, a butter cake is a cake made with butter, baked in a bundt pan, then drizzled with a hot and sweet buttery syrup while the cake is warm. As the cake cools, the syrup infuses every bite of the cake, keeping it super soft and light and drenched in flavor.

This Key Lime Butter Cake version has so much lime flavor in every single bite. There is key lime juice and zest in the cake, the syrup, and in the drizzle on top. There is no searching to find the lime flavor in this cake; it practically bursts in every bite.

I don’t think I’ve told you guys this, but I started working with a trainer. She comes to my house three times a week, not only to give me a workout that leaves me sweaty and sore, but also to help me with nutrition and motivation. She’s making me keep a food journal and giving me all sorts of tips about what to eat and supplements that will help my metabolism and cut the sugar cravings. My life is a contrast in terms: me, trying to eat well, working out hard, then baking a cake. Sometimes I just shrug and say, yes, this is really my life.

It’s also a bit like an alcoholic working in a bar: once that cake is in my kitchen it’s almost impossible to avoid it. I’m trying to build my willpower, and most of the time it doesn’t work, but I’m super proud of myself: I managed to only taste this cake before I froze it. (Yes, you can freeze cake.) I’m hosting a brunch for 30 people on Easter, so I know I can serve it to them.

#winningatmydiet #atleastforTuesday

slice of key lime butter cake on white plate

This key lime cake is made without gelatin, which I know a lot of people are looking for. It does start with a cake mix, but the secret is safe because no one will ever know, as long as you bury the box in the trash.

It may seem weird that I started with a lemon cake mix, but this cake doesn’t taste like lemon, or even like lemon lime cake. It tastes totally like key lime, because I added so much to the recipe. I used lemon cake mix because key lime cake mix is hard to find, and because I really wanted that citrus flavor. You can start with a yellow or white cake mix too, if you want, but you’ll want to adjust the ratio of lime juice to water and lime zest (see my notes in the recipe). If you happen to be able to find a key lime cake mix (a few brands make it as a specialty flavor once in awhile), you can use that too.

The secret to the buttery key lime cake flavor is a few different ingredients that mix to make the best cake you’ll ever eat:

Key Lime Butter Cake is an easy cake recipe drenched in key lime flavor: in the cake, syrup, and drizzle. You won’t be able to stop at one bite!

slice of key lime butter cake on white plate with challenge butter in the background

The first ingredient you must have in any butter cake is, of course, butter. As you all know, I absolutely love Challenge Butter. It’s the only butter I buy and use in blog life and real life because it’s the best. I’ve eaten it since I was a child (it’s my dad’s favorite). Challenge makes their butter with no added hormones or artificial ingredients, which makes the butter taste the best. When you’re making something like a butter cake, you want to use a butter you can trust, and for me, that’s Challenge Butter.

How to make an easy Key Lime Butter Cake:

  1. Start with a cake mix – I used lemon, but you can also use yellow or white, or key lime if you can find it.
  2. Add a box of pudding to the cake. This keeps the cake super tender! I used lemon, but you can use vanilla instant pudding mix also.
  3. Don’t spend hours trying to squeeze juice out of key limes, unless you really feel like it. I use a bottle of key lime juice I find in the juice aisle (near the lemon and lime juices). I know usually fresh is best, but not for key lime juice.
  4. If you can’t find key limes for zest, regular limes are fine.
  5. Make the sauce while the cake is cooling. It takes just a few minutes.
  6. You can skip the glaze but it packs another punch of key lime flavor, so I am in favor of keeping it!

This key lime cake is one of the best you’ll ever make, I promise. And even through there are three different parts, it’s super easy to make!

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Key Lime Butter cake

An EASY Key Lime Butter Cake is a cake that explodes with lime flavor. The cake is soaked with lime syrup and the whole thing is topped with key lime drizzle - this cake screams key lime dessert!
4.25 from 4 votes
Prep Time 20 minutes
Cook Time 45 minutes
Yield 12 -16 servings
Serving Size 1 /16 cake



  • 1 box 15.25 ounces lemon cake mix1
  • 1/2 cup 113g Challenge unsalted butter, melted
  • 3/4 cup 178ml water2
  • 1/4 cup 59ml key lime juice3
  • 4 large eggs
  • 1 teaspoon butter extract optional; it pumps up the butter flavor of the cake
  • 1 3.4 ounce box instant vanilla or lemon pudding mix4
  • 1 tablespoon lime zest about 1 medium lime or 2-3 key limes


  • 3/4 cup 149g sugar
  • 1/4 cup 57g Challenge unsalted butter
  • 4 tablespoons 59ml Key Lime juice
  • 1 tablespoon lime zest about 1 medium lime or 2-3 key limes
  • 1 teaspoon vanilla extract
  • Powdered sugar for dusting


  • 1 cup powdered sugar
  • 2-3 tablespoons key lime juice


  • Preheat oven to 350°F. Spray a 12-cup bundt pan with nonstick cooking spray (the kind with flour) or butter and flour it.
  • Use a hand mixer or whisk to beat the cake mix, butter, eggs, water, lime juice, extract, zest, and pudding mix until a thick batter forms. Pour into prepared pan.
  • Bake for 35-45 minutes, or until a toothpick comes out with just a few crumbs. Remove the cake from the oven and cool for 10 minutes but keep it in the pan.
  • While the cake is cooling, make the sauce. Melt butter in a small saucepan over medium low heat. Stir in the sugar, zest, and juice and cook until it just simmers (bubbles around the edges). Remove from heat and stir in the vanilla.
  • Poke several holes in the cake using a long skewer and pour the butter sauce over the cake. Cool in pan completely, then remove to serving plate.
  • Make the drizzle: whisk together powdered sugar and lime juice. Drizzle over cooled cake.
  • Store loosely covered. Best within 2 days.

Nutrition Information

Serving: 1/16 cake | Calories: 277kcal | Carbohydrates: 40g | Protein: 2g | Fat: 12g | Saturated Fat: 6g | Cholesterol: 69mg | Sodium: 221mg | Fiber: 1g | Sugar: 29g

Nutritional information not guaranteed to be accurate

I can never get enough citrus flavor! Check out my other key lime favorites:

A No Bake Key Lime Eclair is the perfect summer dessert!

Easy No Bake Key Lime Eclair on a white plate with a fork

Craving Key Lime Cheesecake? I got it covered!

Key Lime Cheesecake on a white plate with a drink in the background

Key Lime Pie is the BEST citrus pie I’ve ever had!

Close up of key lime pie in a glass pie dish

This post is sponsored by Challenge Dairy. All opinions are 100% my own. I promise to only endorse products I really love and Challenge is one of them!

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Recipe Rating

19 CommentsLeave a comment or review

  1. Hi, do you think it would make a difference if I made this in an Angel Food Cake pan (9 3/8 x 4 1/4)

  2. The ingredients and the directions don’t match up. You have butter listed for the cake, but it’s not included in the cake step. You also have “water” listed in the directions for the sauce, but only lime juice is listed in the ingredients. I tried to follow this based on my best guess, but this needs a little proofreading. 

    Smells good so far tho! 

  3. Thinking og making this cake but have sone questions about the directions.
    In step 1 it says to mix in cake mix eggs Milk ? ?
    Didnt see any milk in ingredients
    It also says to add salt in the sauce but again I dont see any salt listed .
    Could you shed some light on this Thank you

  4. I’m not a key lime fan, but after watching your mesmerizing video, I would love to try this. You have some ingenious tricks up your sleeve for amping up the flavor in this cake. It looks absolutely delicious. Once again, another amazingly creative recipe, Dorothy.

  5. I cannot wait to try this one! My sister loves Key Lime so this would be the perfect Easter treat for her!

    Way to go on the trainer and the journal, gah it’s so hard working in this world and keeping on track!! ❤️

  6. I love key lime pie and anything key lime inspired so I know I would love this cake!

    Congrats on working with a trainer! That is awesome and I am proud of you!