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Key Lime Cupcakes From Box Cake - Bright, Tangy, and Easy

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Prep Time 15 minutes
Cook Time 20 minutes
Total Time 35 minutes
Servings: 12 servings
Ingredients Method

Ingredients
  

  • 1 box white or vanilla cake mix (15.25 ounces)
  • 3 large eggs
  • 1/2 cup neutral oil (canola or vegetable)
  • 3/4 cup whole milk (or 2% in a pinch)
  • 1/3 cup key lime juice (fresh if possible; bottled works)
  • 1 tablespoon key lime zest (from about 6–8 key limes, or 1–2 regular limes)
  • 1/3 cup sour cream or plain Greek yogurt
  • 1 teaspoon vanilla extract
  • 1 cup (2 sticks) unsalted butter, softened
  • 3 1/2–4 cups powdered sugar
  • 2–3 tablespoons key lime juice
  • 1 teaspoon key lime zest
  • Pinch of salt
  • 1–2 tablespoons heavy cream or milk, as needed

Method
 

  1. Prep the pan: Heat oven to 350°F (175°C). Line a 12-cup muffin tin with liners. For mini cupcakes, use 24 liners and reduce bake time.
  2. Mix the wet ingredients: In a large bowl, whisk eggs, oil, milk, lime juice, vanilla, and sour cream until smooth.
  3. Add the dry: Sprinkle in the cake mix and lime zest. Stir with a spatula until just combined. Do not overmix.
  4. Fill and bake: Divide batter among liners, filling each about 2/3 full. Bake 16–20 minutes, or until the tops spring back and a toothpick comes out clean.
  5. Cool completely: Let cupcakes rest in the pan 5 minutes, then transfer to a rack. Cool fully before frosting.
  6. Make the frosting: Beat softened butter on medium-high until fluffy, about 2 minutes. Add 3 1/2 cups powdered sugar, lime juice, zest, and salt. Beat until smooth. Adjust with more sugar for thickness or a splash of cream for softness.
  7. Frost and garnish: Pipe or spread frosting on cooled cupcakes. Top with zest, tiny lime wedges, or a sprinkle of graham crumbs for a “pie” vibe.