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Key lime cupcakes with creamy buttercream frosting on a decorative plate

Key Lime Cupcakes with Buttercream Frosting

Bright, tangy, and impossibly good, these Key Lime Cupcakes with Buttercream Frosting are a citrus treat that brightens a weeknight and steals the show at parties.
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Prep Time 30 minutes
Cook Time 20 minutes
Total Time 50 minutes
Servings: 12 servings
Course: Dessert, Snack
Cuisine: American, Tropical
Calories: 250
Ingredients Method Notes

Ingredients
  

For the Cupcakes
  • 1.5 cups 1 ½ cups all-purpose flour Use a spoon-and-level method to avoid dense cupcakes.
  • 1.5 teaspoons 1 ½ tsp baking powder
  • 0.25 teaspoons ¼ tsp salt
  • 0.5 cups ½ cup unsalted butter, softened Use unsalted butter for better control of salt level.
  • 1 cups 1 cup granulated sugar
  • 2 large 2 large eggs Use room temperature eggs for proper creaming.
  • 2 teaspoons 2 tsp pure vanilla extract
  • 0.5 cups ½ cup buttermilk Use full-fat for best texture.
  • 2 tablespoons 2 tbsp key lime juice (fresh) Fresh juice is preferred over bottled.
  • 1 tablespoons 1 tbsp key lime zest
For the Buttercream Frosting
  • 0.75 cups ¾ cup unsalted butter, softened
  • 3 cups 3 cups icing sugar, sifted Sifting is important for a smooth texture.
  • 2 tablespoons 2 tbsp key lime juice (for frosting)
  • 1 teaspoon 1 tsp lime zest (for frosting)
  • 1–2 tablespoons 1–2 tbsp cream or milk (as needed for frosting) Add until you reach piping consistency.

Method
 

Preparation
  1. Preheat the oven to 350°F (175°C). Line a 12-cup muffin pan with paper liners and set aside.
  2. Cream the ½ cup softened butter with 1 cup granulated sugar until light and fluffy, about 3–4 minutes.
  3. Add the eggs one at a time, mixing well after each, then stir in 2 tsp vanilla.
  4. In a separate bowl, whisk together the 1 ½ cups all-purpose flour, 1 ½ tsp baking powder, and ¼ tsp salt.
  5. Alternate adding the dry ingredients and ½ cup buttermilk to the butter mixture, beginning and ending with the dry ingredients.
  6. Fold in 2 tbsp key lime juice and 1 tbsp key lime zest.
  7. Divide batter evenly among the 12 liners and bake until a toothpick comes out clean, about 16–20 minutes.
  8. Cool completely before frosting.
Buttercream Frosting
  1. Beat ¾ cup softened unsalted butter until creamy.
  2. Gradually add 3 cups sifted icing sugar, beating on low to combine and finishing on medium.
  3. Add 2 tbsp key lime juice and 1 tsp zest.
  4. Add 1–2 tbsp cream or milk to reach piping consistency.
  5. Chill briefly if the frosting becomes too soft, then pipe or spread onto cooled cupcakes.

Notes

Store frosted cupcakes in an airtight container in the refrigerator for up to 4 days. For longer storage, freeze unfrosted cupcakes for up to 3 months.