In the winter months, there's nothing like the bewitching, slightly exotic flavor of Key limes or the larger regular limes (a.k.a. Persian) to transport you mentally to some warm tropical spot, preferably an island with an endless beach. This cake, with its tart lime filling offset by billowy drifts of sweet, marshmallow-like frosting, should do the trick.
Key limes are smaller than Persian limes and often come packed in a net bag, but don't despair if you can't find them. Persian limes make an excellent substitute (see Cooks' Notes, below, for more details on buying limes). Another helpful hint: Because there's grated zest in both the cake and the filling, grate all the zest you need first, before you start juicing.
Recipe information
Total Time
2 hours (includes 1 hour cooling time for filling)
Yield
Makes 10 to 12 servings
Ingredients
Cake:
2
2
1
2
1
4
1
1
1
Filling:
3
1
3
3
2
3
2
Frosting:
2
3
2
2
1
1
1
Special Equipment
2
Need to make a substitution?
Preparation
For Cake:
Step 1
Heat oven to 350°F. with rack in middle. Butter cake pans, then line bottoms with rounds of parchment. Dust pans with additional flour, knocking out excess.
Step 2
Sift flour, baking powder, and salt together into a bowl.
Step 3
Beat together butter and sugar in a large bowl with an electric mixer (or a stand mixer fitted with the paddle attachment) at medium-high speed until pale and fluffy, about 3 minutes. Beat in eggs one at a time, beating well after each addition. Beat in zest and vanilla and continue beating until light and fluffy, 3 to 5 minutes more. At low speed, add flour mixture in 3 batches alternately with milk, beginning and ending with the flour mixture and mixing until batter is just smooth.
Step 4
Divide batter between cake pans, spreading it evenly. Bake until a wooden toothpick inserted in the center of each cake comes out clean and cakes begin to pull away from sides of pans, 20 to 25 minutes.
Step 5
Cool for 15 minutes in pans on racks. Run a thin knife around sides of pans, invert cake layers onto racks, and cool completely.
For Filling:
Step 6
Whisk together sugar, cornstarch, and salt in a heavy 2-quart saucepan, then whisk in 3/4 cup water and juice until smooth. Whisk together eggs in a medium heat-proof bowl until well combined.
Step 7
Bring juice mixture to a boil over medium heat, stirring with whisk, then reduce heat and continue to cook at a slow boil, stirring with whisk, 1 minute (mixture will be thick). Remove pan from heat.
Step 8
Add half of hot juice mixture to eggs in a slow stream, stirring with whisk. Stir egg mixture into juice in pan and cook over medium-low heat, stirring, just until it reaches a simmer. Remove pan from heat and add butter and zest, stirring until butter is melted.
Step 9
Cover filling with a buttered round of wax paper or parchment paper and chill until cold, about 1 hour.
For Frosting:
Step 10
Combine frosting ingredients in a large bowl with electric mixer (or stand mixer fitted with the whip attachment). Beat at high speed until frosting is thick and fluffy, 3 to 5 minutes.
Assemble Cake:
Step 11
Halve each cake horizontally with a long serrated knife. Put 1 layer on a cake stand or a large plate and spread with one-third of filling (about 2/3 cup).
Step 12
Stack remaining cake layers using half of remaining filling between each layer.
Step 13
Spread top and side of cake generously with frosting.