This key lime frosting is a creamy buttercream frosting that's just sweet enough with the perfect tangy citrus flavour. It is beautiful, too, with flecks of lime zest visible throughout. You can use this delicious and versatile frosting on so many different kinds of cakes, cupcakes and cookies.

A cupcake decorated with key lime frosting.

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Ingredients
Substitutions
Variations
Instructions
What to use it with
Equipment
Storage
Tip for Success
📖 Recipe

Key lime frosting decorated cupcakes on a wooden board.

I can't stand sickeningly sweet icings. This one is just a little bit sweet with the perfect tanginess. I was licking it off the spoon. It's so good! Something about key lime just screams summertime to me. I can definitely see myself using this frosting often.

I created this frosting to go with this tasty lemongrass cake, but like I said - it is so versatile. And for another deliciously infused frosting recipe, I recommend that you try this tasty frosting made with real, fresh cherries that is super popular for good reason.

Ingredients

Key limes (zest and juice) - Key limes are the adorable, miniature version of the citrus we know and love. These limes are less tart and more aromatic than the Persian lime (standard grocery store variety). This makes them perfect for using in a frosting.
Unsalted butter
Pure vanilla extract - Use pure rather than artificial vanilla extract, if possible. The difference in flavour is quite noticeable.
Salt
Confectioner's sugar
Milk

See the recipe card below for quantities.

Cupcakes decorated with key lime frosting.

Substitutions

Key limes - You could substitute key limes with regular limes in this recipe. However, keep in mind that regular limes are more tart and less aromatic than key limes.

Variations

You could modify this recipe to use with any kind of citrus! Lemon, lime, tangerine, mandarin orange, to name a few. You may find yourself needing more or less sugar depending on the tartness of the citrus you choose.

Instructions

Zest and juice your key limes. Always zest before juicing.

Butter whipped with key lime zest, salt, and vanilla in a stand mixer bowl.

Using your stand mixer (or elbow engines), mix the butter, zest, salt, and vanilla extract together on medium speed until nice and creamy.

Confectioner's sugar whipped into frosting in a stand mixer bowl.

Alternately add and mix in the icing sugar and lime juice in the following order: ⅓ of the confectioner's sugar, ½ of the lime juice, ⅓ confectioner's sugar, ½ lime juice, ⅓ confectioner's sugar. Mix well between each addition.

Finally, mix in the milk. You can add more milk or confectioner's sugar to adjust the consistency if necessary.

What to use it with

This key lime frosting is very versatile and would be great to use on many different kinds of cakes, cupcakes, or cookies. I made it to pair with this lemongrass cake, however, here are some other flavours that it would go wonderfully with:

Vanilla (like the cupcakes I photographed this frosting on)
Lemon
White chocolate
Strawberry
Raspberry
Gooseberry
Coconut
Mango
Sugar (i.e. sugar cookies)

A close up of key lime frosting and white flowers.

Equipment

I used my Kitchenaid stand mixer with a paddle attachment to whip up this frosting. You can, however, also make this frosting using a hand mixer or by hand. It is also handy to have a microplane zester for all of your zesting needs.

stand mixer

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microplane zester

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Storage

Store in an airtight container in the refrigerator for up to 1 week. You can also freeze this frosting in an airtight, freezer-safe container for up to 3 months. I do find that using it fresh is the best way to enjoy the lovely key lime aromatics.

Whether freezing or refrigerating, set it out to bring it back to room temperature before using and beat it until it is creamy again. You can tweak the consistency with more milk if necessary.

A key lime frosting decorated cupcake on a serving plate.

Tip for Success

Room temperature - Dairy should be room temperature for this recipe. Cold ingredients simply won't combine properly, resulting in uneven lumps. Set them out an hour or two before you start.
Stand mixer attachment - If you make this recipe using a stand mixer, make sure to use a paddle attachment and not a whisk. The whisk will cause air bubbles.
Consistency - Adjust the consistency of the frosting with more milk or confectioner's sugar. If the frosting is too thin, mix in tiny amounts of sugar until you have reached your desired consistency. If it is too thin, do the same with milk.

📖 Recipe