Key Lime Coconut Cake

Prep Time: 1 hour
Cook Time: 38 minutes
Total Time: 1 hour 38 minutes
This key lime cake is the ultimate summer party cake. It's pummeled with crunchy toasted coconut and boasts the juice from 5 limes.
Author: Natasha of
Skill Level: Medium
Cost to Make: $10-$15
Servings: 9 " round cake


1 Recipe for Sponge Cake (makes two 9-inch cakes)

Key Lime Syrup Ingredients:

  • 1/4 cup freshly squeezed lime juice from 3 medium limes
  • 3 Tbsp granulated sugar
  • 3/4 cup warm water

Key Lime Frosting Ingredients:

  • 8 oz cream cheese softened
  • 1 cup granulated sugar
  • 16 oz cold sour cream full fat
  • 3 Tbsp lime juice freshly squeezed (from 2 medium limes)
  • 1 Tbsp lime zest from 2 medium limes

Topping Ingredients:

  • 2 cups 7 oz sweetened shredded coconut


How to Make Key Lime Cake:

  1. Toast coconut at 350˚F in a small baking pan in oven, stirring a few times, especially towards the end, until golden and dry, 7 to 10 minutes. Set aside to cool.
  2. Make 4-Ingredient Sponge Cake and set aside to cool. Get the recipe on and be sure to watch the video tutorial.

How to Make Key Lime Frosting:

  1. In the bowl of your mixer fitted with whisk attachment, beat together cream cheese and 1 cup sugar on high speed 3 minutes until whipped, scraping down the bowl as needed.
  2. Beat in 16 oz cold sour cream until smooth (1 min on high). Add lime zest and juice and beat to combine (1 minute on high). Refrigerate frosting if not using right away.

How to Make Key Lime Cake Syrup:

  1. In a measuring cup, combine 1/4 cup fresh lime juice, 3/4 cup warm water and 3 Tbsp sugar. Stir to dissolve the sugar and set aside.

How to Assemble Key Lime Cake:

  1. Slice cake layers in half with a serrated knife. Place the first layer, cut-side-up on a cake platter. Brush with 1/4 of the lime syrup. Top with a generous amount of cream. Repeat with remaining cake layers then cover the entire cake with remaining cream.
  2. Cover the entire cake generously with toasted and cooled coconut flakes, using your hands to scoop coconut onto the sides, pressing gently to adhere. The coconut flakes are crispiest if served right away but it is easier to slice the cake once it's had a chance to set in the refrigerator for about 2 hours.

Recipe Notes

Cake can be covered and refrigerated up to a week. I've also frozen portions of it then thawed with great results - I loved it still partially frozen.