Thursday, March 31, 2011

Triple Lime Cake for an office birthday

This is a cake I created for a co-worker recently. Last year I made her a Lemon Mascarpone cake and the year before that a chocolate cake, so I didn't want to repeat myself. I had a bag of coconut chips from burning a hole in my pantry and had limes on the brain, so my "recipe" was a hybrid of Fine Cooking's Triple Lemon Cake (substituting limes) and a Key Lime & Coconut Cake from the Sweet Treats blog. It was well received as most office treats are but IMHO was a little dry. Why? The cake itself may have been slightly overbaked to begin with, and then the layers were frozen for a couple days. The curd filling had oozed out during assembly so there was even less moisture. And although I'd used a simple syrup to put back some of the moisture lost during freezing, it wasn't enough. If I were to do this cake again I'd only make the two layers and split them as per the original recipe, instead of doubling the recipe to make three 9" layers (and six cupcakes). That way more simple syrup would've been absorbed and one more layer of curd filling would've been added, ensuring a moister cake overall. Well, at least it looked pretty good. You may be wondering about a couple of different lime products listed in the recipes; I only used them because they were hanging around in the kitchen. True Lime and True Lemon are powdered extracts so they add a punch of flavor without watering anything down.

Triple-Lime Layer Cake
Adapted from Fine Cooking's Triple-Lemon Layer Cake

Lime Cake (makes two 8" dia. x 2" cakes):
9-1/4 oz. cake flour
2-3/4 tsp. baking powder
1/4 tsp. table salt
1-3/4 cups granulated sugar
2 Tbs. finely grated lime zest
6 oz. unsalted butter, softened
8 oz. whole milk, at room temperature
5 large egg whites, at room temperature
1/4 tsp. cream of tartar

Lime Curd Filling (read notes in directions before making!):
3 oz. unsalted butter, softened
1 cup granulated sugar
2 large eggs
2 large egg yolks
2/3 cup lime juice
Pinch of salt
1 tsp. finely grated lime zest
1/8 tsp. Boyajian Lime Oil

Simple Syrup:
1 cup granulated sugar
1/4 cup lime juice
1/4 cup water
1 tbsp. lime zest

Lime Frosting:
1 cup whipped cream
8 oz. unsalted butter, softened
4 oz. cream cheese, softened
2 Tbs. lightly packed finely grated lime zest
3-1/2 cups sifted confectioners’ sugar
3 Tbs. lime juice
2 packets of True Lime

For decoration:
1/2 lb. coconut chips, lightly toasted
Lime zest or lime slices
Silver dragees

Cake: Place a rack in the middle of the oven and preheat to 350°F. Butter and flour two 8" x 2" round cake pans. Sift the cake flour, baking powder, and salt together in a medium bowl. Pulse 1/4 cup of the sugar with the zest in a food processor until well combined. In a large bowl, beat the butter and lime sugar with an electric mixer on medium speed until light and fluffy (about 1-1/2 minutes). Add the remaining sugar and beat until smooth (about 1-1/2 minutes). Beat in a quarter of the milk just until blended. On low speed, add the flour mixture alternatively with the milk in three batches, scraping the bowl with a rubber spatula; beat just until blended. In another bowl, beat the egg whites with an electric mixer (with clean beaters or a whisk attachment) on medium speed just until foamy. Add the creme of tartar, increase the speed to medium high, and beat until the whites form stiff peaks when the beaters are lifted. Add a quarter of the whites to the batter and gently fold them in with a rubber spatula; continue to gently fold tin the whites, a quarter at a time, being careful not to deflate the mixture. Divide the batter evenly between the prepared pans. Smooth the tops with a spatula. Bake until a pick inserted in the centers comes out clean, about 35-40 minutes. Let cool in the pans 10 minutes. Run a table knife along the sides of the pans and carefully invert each cake out onto the rack. Flip them right side up and let them cool completely.

Curd: Beat the butter with the sugar until it’s light and fluffy. Slowly beat in the eggs and yolks. Beat for 1 minute more, then stir in the lime juice. The mixture will look curdled. Cook the mixture over low heat until it becomes smooth, then increase the heat to medium and cook, stirring constantly, without letting it boil, until it thickens enough to leave a path on the back of the spoon when you drag your finger through it (170°F). Remove from the heat and stir in the lime zest. Press plastic wrap on surface to prevent a skin from forming and chill in the refrigerator. Note: my curd ended up being very thin even after refrigeration and most of it oozed out during assembly. If this happens to you, I suggest fixing it right away with cornstarch dissolved in lime juice and cooking the curd gently until thickened; or use a couple more egg yolks to begin with.

Simple syrup: In a saucepan, combine water, lime juice and zest. Stir sugar in to dissolve. Bring the mixture to a boil on the stovetop and cook for one minute. Allow to cool.

Frosting: Beat the whipped cream until stiff peaks form and set aside. In another bowl, beat the butter, cream cheese and lime zest until light and fluffy. Add the confectioners sugar in batches and beat until light and fluffy. Add the lime juice and beat for one minute. Fold in the whipped cream until completely blended.

Assembly: Split cake layers. Poke each layer liberally with a skewer, brush with simple syrup and spread curd filling between layers while stacking. With the frosting, fill in gaps and apply a crumb coating. Chill the cake until the frosting firms up, about 1/2 hour. Spread remaining frosting decoratively over the top and sides of cake. Apply coconut to the sides of the cake. Scatter the top with lime zest and silver dragees, or garnish as shown with extra dollops of frosting, quartered lime slices and dragees.