In our house, like many I guess, the tradition is that the birthday person gets to pick his or her birthday cake and I create it. Some years ago, we went from my go-to domed ice cream cake creations (molded in the yellow Pyrex bowl) which were pretty easy to assemble and accommodated all sorts of flavor combos, to requests which were a bit elaborate for my skill level (read: patience with fiddly things). For some reason – my bull-headedness perhaps – I would accept each challenge with generally reasonable success. Quadruple chocolate ice cream layer cake? Done! Forty-seven-fruit-flavors-in-one ice cream layer cake? Done. Banoffee pie as ice cream layer cake? Uh… Anyway.
This year for Locust the Younger’s birthday, he really wanted a key lime pie but announced somewhat arbitrarily (where’d he get that trait?) that pie does not rise to the level of birthday celebration dessert and he would very much appreciate if I would turn key lime pie into a birthday cake. I briefly contemplated making two pies and stacking them with an Italian meringue for glue and coverage (icing, to the novice) and stashing it in the deep freeze for architectural integrity but then thought while sticking to the letter of the request, it certainly wasn’t in the spirit.
So I went a’hunting for a recipe. Oddly, none existed that: 1) I liked the read of; 2) was made with homemade ingredients (I mean, really, I could just go to Baskin Robbins, right); and 3) I could find in my down-the-rabbit-hole search (please see my note above re: fiddly things and my patience level).
Drawing on my inner Magellan, I struck out on my own and plotted a cake that, much like a well-OldSpiced fella, layered on multiple components of the primary flavor (key lime) for maximum taste benefit. Hence, the lime layer cake, lime ice cream, and lime whipped cream. The overall effect is definitely key lime pie but with all the pomp and fiddliness required of a locust-worthy birthday cake.
Fair warning, this is a many-stepped recipe but can be done (and should be to retain some semblance of sanity) over the course of a few days – except the whipped cream which should be last-minute(ish) – stashing each step as you go until ready to assemble just before serving.
PRE-RECIPE CAVEAT: I know the “key limes” we can get are not key limes. I am making this in the spirit of key lime using the zest of Persian limes (the big ‘uns we can get in the grocery store) and Nellie & Joe’s key lime juice. The Persian limes, to me, are far too bitter (for lack of a better word) to use the juice. Fear not that I waste that deliciousness. It makes fine limeade and even finer margaritas.
PRE-RECIPE SUGGESTION: This cake takes a LOT of lime zest. Just zest the limes all at once and keep the zest in an air-tight container in the fridge until you need it. I have Pyrex dishes with click-on tops that work great.
The cake layer is a pretty straight-forward recipe that is lime-forward. I’ve been watching sommelier Ted Talks, can you tell. I’ve got no photos because I was in the cake making mode and not the photographer mode (aka … I forgot). If you’ve got questions, let me know and I’ll clarify.
The ice cream layer is easy-peasy. Toss everything into the Whizzerator 5000 (Do NOT put the lime zest in first or you’ll be scraping it off of the blade. You are welcome to learning from my mistakes.) Once made and chilled, put into an ice cream maker and churn until it’s the texture of soft serve. Fair warning, this ice cream is very easy to make and consume before it ever sees the light of cake production. Buy ingredients for a second batch if you (or the heathen(s) you are making the cake for) somehow talk you into the idea that a taster batch is in order.
The graham cracker crust layer is made with the ingredients of a key lime pie crust but tamped into the bottom of a springform pan (the same that you’ll eventually assemble in) with a much lighter hand at tamping than a regular crust. There is no need for structural soundness, just the crunch, and if tamped too firmly is a bugger to slice through when frozen. I know this from experience. Also, if it breaks apart at any point, just puzzle-piece it together when assembling. Please see pic above. No one will ever know.
My only assembly pictures are the two above … once I got started, there was no stopping for photos. I really need a photographer. Or more skill.
To the cake assembly… Into the lined (sides and a bottom lifting “strap” of parchment) pan place one cake layer, half of the ice cream, the graham cracker crust layer, the second cake layer and the rest of the ice cream. Smooth the ice cream and then take the whole pan in both hands and gently but firmly bonk on the counter two or three times to get any air bubbles out. Smooth again if necessary. Freeze until the top layer of ice cream is no longer tacky (about an hour) and then very thoroughly wrap the entire thing – cake, pan, and sleeve – in plastic wrap.
While it can be ready to decorate with whipped cream after about six hours, letting it sit overnight gets you a more solid cake (that’s a good thing) with more melded flavors. Once you get the whipped cream ready and into a piping bag (or just a knife for swirls if that’s what you’ve got), take the cake out of the springform pan and remove all the parchment. Place on your serving plate, decorate with whipped cream and then park in the refrigerator until ready to serve. Can easily stay up to an hour in the fridge without getting melty. If placed carefully back in the freezer – if you’ve got the room – it can be made even further in advance with the understanding that anything unwrapped will eventually absorb any odors. That could make for bad cake joo-joo.
A further side note re: pre-making the cake. After the initial serve, I did wrap the cake – whipped cream and all – in plastic wrap and stored in the freezer. The only downside was that the nice swirls of whipped cream got a little smooshed. If you carefully placed toothpicks to hold the plastic wrap off of the cake, I don’t see why you couldn’t get it ready through frosting before stashing – especially if you’re having a party, this would make life a lot easier.
It is not a difficult cake to make; just has lots of parts. And it was very, very well received by key lime pie aficionados in this house. Happy happy all around! And that’s that. Say good night, Gracie. Good night, Gracie!
Aiden’s Key Lime Pie Ice Cream Birthday Cake
1 1/2 sticks (12T) (170g) unsalted butter, softened
1 1/2 cups (300g) sugar
4 large eggs, room temperature
3 cups (342g) cake flour
1/2 teaspoon (3g) salt
1 1/2 teaspoons (7g) baking powder
1/2 teaspoon (3g) baking soda
1 cup (242 g) milk
1/4 cup (57g) lime juice
1/4 cup (53g) vegetable oil
zest of 2 limes
1 tsp vanilla extract
GRAHAM CRACKER LAYER
5 oz graham crackers (1/3 of a package of Nabisco Honey Grahams) NOT cinnamon-sugar or sugar-topped
5 TBS unsalted butter, melted
1/3 cup sugar
ICE CREAM LAYER
2 cups sweetened condensed milk
2 cups heavy whipping cream
1.5 cups lime juice
2 tsp grated lime zest
1-2 cup heavy whipping cream
3-6 TBS confectioners sugar
1-2 TBS lime zest
FOR THE CAKE:
Preheat the oven to 350 degrees
Grease two 9 inch pans and line with parchment circles (or grease and flour the pans)
In a medium sized bowl add the cake flour, baking powder, baking soda, salt and zest of 2 limes. Whisk to blend and set aside.
In another bowl, add the milk, vegetable oil, lime juice, and vanilla extract. Whisk to blend and set aside.
In the bowl of a mixer with the paddle attachment, beat the butter until smooth. Gradually add the sugar and mix on medium speed 3 to 5 minutes until it is light in color and fluffy.
Add the eggs one at a time, mixing until each yolk is dispersed. Stop the mixer and scrape from the bottom with a spatula after each egg addition.
Add the dry mixture and the wet mixture alternately, beginning and ending with the flour (3 additions of flour and 2 of milk). Mix just until combined and smooth.
Pour the batter into the prepared pans, smoothing the tops with a spatula. Bake at 350 degrees, starting to check for doneness at 25 minutes (until a toothpick in the center comes out clean or with only a few crumbs attached). Let the cakes cool in the pans 10 minutes and then remove from pan onto a cooling rack. Peel off the parchment if using.
When completely cooled, wrap in plastic wrap and put into the freezer until ready to assemble.
FOR THE GRAHAM CRACKER LAYER:
Preheat oven to 350. Put a piece of parchment into the bottom of a 9-inch springform pan and clamp.
Break up graham crackers and pulse in the food process and until all the big pieces are broken down. Add the sugar and whiz until the texture of sand. Add the melted butter and pulse until combined.
Press the crumbs into the springform pan and lightly tamp down in an even layer.
Bake for 8 minutes. Place springform pan onto a cooling rack for 10 minutes. Unhinge the pan and remove the graham cracker crust. Cool completely on the rack.
FOR THE ICE CREAM LAYER:
Combine all of the ingredients in a blender (or with a whisk). Chill until cold and put into an ice cream maker; churn for 15 minutes. If not using right away, put into a freezer-safe container and freeze until ready to use.
Just before assembling the cake: Whip all ingredients together with a balloon whisk or the whisk attachment of a mixer until you have stiff peaks.
Create a parchment collar in a 9-inch springform pan to raise its sides by 3-4 inches. Place one long piece of parchment into the bottom extending up the sides to make cake removal easier. Place one cake layer in the springform pan.
Put half of the ice cream on the cake, smoothing it down the sides and over the top.
Place the graham cracker crust down.
Put the second cake layer on the graham cracker crust – flat side up – and then put the remaining ice cream on the cake, making sure it goes down the sides. Smooth the top.
Wrap springform pan entirely in plastic wrap. Freeze at least 6 hours, overnight is better.
Half-an-hour before you are ready to serve, make the whipped cream.
Remove the cake from the springform pan and place on a serving platter/plate.
Put whipped cream into a piping bag and decoratively pipe around the cake. Feel free to decorate with lime slices.
For best service, let sit at room temperature 20 minutes from freezer or hold in refrigerator for up to one hour. Slice and enjoy!