Key Lime Cupcakes with Tangy Lime Curd Filling

These Key Lime Cupcakes are packed with bright, tart key lime flavor. The cupcakes are buttery, soft, and moist, with lime flavor in every bite. Each one is filled with tangy lime curd and finished with a lime cream cheese frosting—perfect for parties or any celebration.

They disappear quickly—my taste testers can confirm!

Key Lime Cupcakes on a marble cake plate, topped with swirls of cream cheese frosting, lime curd, and a lime slice for garnish.

Why you’ll love these Key Lime Cupcakes:

Intense Lime Flavor – Lime zest is rubbed into the sugar for the cupcakes, the lime curd is sharp and tangy, and the frosting includes lime juice for an extra lift.
Fluffy & Moist – The cupcakes are tender and springy. They stay moist in the fridge for 2–3 days and freeze well for up to two months if stored properly. The recipe was tested repeatedly to achieve a consistently light texture.
Simple to Make – The batter uses a reverse creaming approach for ease and great texture. The lime curd takes about 15 minutes to prepare and chills while the cupcakes bake.

A close-up of a lime cupcake with a bite missing, showing the lime curd filling inside.

Ingredient Overview:

The full recipe with exact measurements and directions is in the recipe card below.

Cake Flour – Produces a lighter crumb. Spoon and level or weigh your flour for best results—1 cup cake flour ≈ 115 g.
Sour Cream – Use full-fat sour cream at room temperature.
Butter – Salted butter gives great flavor; unsalted works too. Bring to room temperature.
Eggs – Use large eggs at room temperature.
Milk – Room-temperature milk (2% works well) helps the batter come together.
Vanilla – Use a quality vanilla extract or vanilla bean paste for more flavor.
Vinegar – A small amount improves lift and tenderness.
Lime – Fresh lime juice and zest are best; bottled key lime juice can be used in a pinch.

Substitutions & Variations:

Lime Juice – Bottled key lime juice works for the curd if fresh limes aren’t available, but fresh juice is brighter.

Yogurt – If you don’t have sour cream, full-fat plain yogurt is an acceptable substitute.

Time-Saving Tip:

Short on time? Use a boxed vanilla cupcake mix (add lime zest) and make your own lime curd and frosting to keep the fresh flavor.

How to Make Key Lime Cupcakes:

Step 1: Make the Lime Curd. Cook lime-zested sugar with eggs and lime juice, strain, then stir in butter and vanilla. Chill the curd while you bake the cupcakes. Add green food coloring if desired.

Make-Ahead Tip:

Lime curd can be made up to three days ahead and stored in the refrigerator.

Step 2: Start the Cupcakes. Rub lime zest into the granulated sugar. Whisk the dry ingredients together: cake flour, granulated sugar, brown sugar, baking powder, and salt. Add softened butter and oil and mix until the mixture resembles coarse sand with some buttery lumps.

A bowl of the dry ingredients whisked together.

The butter and oil mixed into the dry ingredients. The mixture has different sized lumps and looks semi-moist and semi-dry.

Step 3: Add Wet Ingredients. Whisk sour cream, milk, water, and vinegar together. Add 2 tablespoons of this mixture to the dry ingredients to begin hydrating them.

A glass measuring cup with the sour cream, milk, water, and vinegar whisked together.

Step 4: Finish the Batter. Lightly beat the eggs and vanilla into the remaining wet mixture, then add the wet mix to the batter in two additions, mixing on low until just combined. The batter should be slightly thick but still tender.

Step 5: Bake. Divide the batter evenly among 16–17 liners, filling about two-thirds full (about 52 g batter per cupcake if you want to be precise). Bake until a toothpick comes out with moist crumbs, then transfer to a wire rack to cool.

Don’t Overfill!

Filling liners too full can cause cupcakes to overflow or collapse. Weighing batter ensures consistent results.

An overhead photo of the cupcake batter in the pan, ready for the oven.

A 3/4 angle view of the baked cupcakes cooling in the pan.

Step 6: Core & Fill. Use a corer or teaspoon to remove a small center from each cupcake, about one-third to one-half down, and fill each cavity with lime curd.

Step 7: Make Frosting & Finish. Beat softened butter, powdered sugar, vanilla, lime juice, salt, and cream cheese until smooth. Pipe two swirls on each cooled cupcake, then use the back of a spoon or offset spatula to create a small well in the center. Add an extra dollop of lime curd and sprinkle with graham cracker crumbs or a lime slice to garnish.

A bird's eye view of the cupcakes on a cooling rack, being cored, filled, and frosted.

Serving & Storing:

Serve right away. Store frosted cupcakes in an airtight container in the refrigerator for 2–3 days. Allow chilled cupcakes to sit at room temperature for 15–20 minutes before serving for best texture, or enjoy them cold if preferred.