key lime pie layer cake

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If you’ve been following this site for awhile, you know my love for Christina Tosi and her method of creating cakes runs deep.

Welcome to The Baker Chick!

Years and years ago I baked my way through her first cookbook Milk Bar, and loved learning how she used cake rings and acetate strips to create truly mind blowing creations. 
Her most recent book, All About Cake, takes this obsession one step further with TONS of amazing and creative cakes that I can’t get enough of. When it came to my own birthday a couple months ago, I had the hardest time deciding which to make. Each one is complex with a cake layer, a crumb or crunch of some sort, “soaks” that absorb into the cake, and fillings and frostings.  
Thanks to an Instagram poll I decided on the Key Lime Pie Layer Cake. A truly amazing creation with a buttery graham cake, tart key lime curd, fresh key lime juice soaking each layer, graham cracker crunch, and liquid cheesecake. The final result is nothing short of amazing, a mix of buttery crumbs and tart custard-y goodness, with that perfect crunch in each bite.  
Best of all these cakes aren’t massive- 6 inches and nicely compact, the perfect size for my family and a few slices to share.
Now don’t be intimidated by all the steps of this process. It seems like a lot but when done one day at a time, the whole thing is super manageable. I like to make the crunch first and leave that in a container for a few days, then the fillings, and on the day I assemble the cake I bake the actual cake part, cool it, then put the whole thing together. It gets popped into the freezer overnight and then removed from the mold and thawed slightly. Then you devour it because it’s just so hard to resist!!!
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Interested in a video of this process? I shared the whole thing in my Instagram story highlights! 
One thing to note- the original Key Lime Pie Layer Cake calls for sour cream frosting instead of the liquid cheesecake. I had a hard time with the consistency though and found it too runny. So I made the liquid cheesecake which is tried and true and was a really wonderful addition here!
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Special Equipment/supplies for this cake:

6 inch cake ring: (This is needed to shape and mold the cake. I have used it for every milk bar-style cake and it’s a great investment!) 
Acetate strips: This roll will last awhile and I have used this for all the Tosi cakes I’ve made as well. 


Key Lime Pie Layer Cake

Key Lime Pie Layer Cake

yield: 1 6 INCH LAYER CAKE
4.7 Stars (3 Reviews)
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Ingredients

For the Graham Crunch

  • 1 1/2 cups graham cracker crumbs (190 g)
  • 1/4 cup milk powder (20 g)
  • 2T sugar (25g)
  • 3/4 tsp kosher salt (3g)
  • 6T unsalted butter, melted (85 g)
  • 1/4 cup heavy cream (55g)

For the Key Lime Curd:

  • 1/2 cup key lime juice (110g)
  • 1/2 cup sugar (100g)
  • 4 large eggs
  • 1/4 tsp powdered gelatin
  • 1 stick (8T) of unsalted butter, very cold, cut into chunks
  • 1/4 tsp kosher salt (1g)

For the Liquid Cheesecake:

  • 8 ounces cream cheese (225g)
  • 3/4 cups sugar (150g)
  • 1 tablespoon cornstarch (6g)
  • 1/2 teaspoon salt (2g)
  • 2 tablespoons milk (40g)
  • 1 egg

For the Graham Cracker Cake:

  • 1 stick unsalted butter, softened (115g)
  • 1 2/3 cups sugar (325 g)
  • 3 large eggs
  • 2/3 cup buttermilk (140g)
  • 1/4 cup key lime juice* (50g)
  • 1/4 cup grapeseed or other neutral oil (I like avocado) (40g)
  • 1 1/4 cups cake flour (150g)
  • 1/3 cups graham cracker crumbs (50g)
  • 1 1/4 tsp baking powder (5g)
  • 1 tsp kosher salt (4g)

For the Graham Buttercream:

  • 2/3 cup graham crunch, recipe below (80g)
  • 1/3 cup + 2T whole milk (100g)
  • 1 1/2 tablespoon unsalted butter, softened (20g)
  • 1T powdered sugar (8g)
  • 1tsp packed light brown sugar (5g)
  • 1/8 tsp kosher salt (1/2 g)
  • 1/2 cup plus 1T key lime juice (65g)

Instructions

For the Graham Crunch:
  1. Heat the oven to 250F. Line a sheet pan with parchment paper or a silicone baking mat.
  2. Toss the graham cracker crumbs, milk powder, sugar, and salt together in a medium bowl.
  3. Whisk the butter and heavy cream together. Add these to the dry ingredients and toss again to evenly distribute. The butter will act as a glue, adhering to the dry ingredients and turning the mixture into a bunch of small clusters.
  4. Spread the clusters on the lined sheet pan and bake until they have darkened in color and smell like toasted, buttery graham heaven, about 20 minutes.
  5. Let the crumbs cool completely before using them in a recipe. The crumbs will keep in an airtight container for 1 week in the fridge or in the freezer for up to 1 month.
For the Key Lime Curd:
  1. Combine the key lime juice and sugar in a blender and blend until the sugar granules have dissolved. Add the eggs and blend on low until you have a bright-yellow mixture. Transfer the contents of the blender to a medium pot or saucepan. Rinse the blender jar out.
  2. Bloom the gelatin by sprinkling it over 2 tablespoons of ice cold water. Let it sit for a few minutes.
  3. Set the pot of ket lime mixture over low heat and whisk regularly as it heats up. Keep a close eye on it as it begins to thicken. Once the mixture starts to bubble up and begin to boil, remove it from the heat and transfer it to the blender. Add the bloomed gelatin, butter, and salt and blend until the mixture is thick, shiny, and super smooth.
  4. Pour the mixture through a fine- mesh sieve into a heatproof container and put it in the fridge until the ket lime curd has cooled completely, at least 30 minutes. The curd can be refrigerated for up to 1 week; do not freeze.
For the Liquid Cheesecake:
  1. Heat the oven to 300°F. Put the cream cheese in the bowl of a stand mixer and paddle on low speed for 2 minutes. Add the sugar and mix for 1-2 minutes until the sugar has been incorporated. Scrape down the sides as needed.
  2. In a bowl, whisk together the cornstarch and salt. Add the milk and egg and whisk until smooth. With the mixer on medium-low speed, stream in the cornstarch-egg mixture. Paddle for 3-4 minutes or until the mixture is smooth and loose.
  3. Line the bottom and sides of a 6×6 inch baking pan with foil. Pour the batter into the pan and bake for 15 minutes. Gently shake the pan. The cheesecake should be firmer and more set near the edges and jiggly and loose in the centre. If it needs it, give it 5 more minutes, check on it again and then another 5 more minutes if needed. If it rises more than a 1/4 inch or begins to brown, take it out immediately.
  4. Cool completely to finish the baking process. Once cool, the cheese cake can be kept for 1 week in the fridge.
For the Graham Frosting:
  1. Put the graham crunch in a blender. Add the milk and puree the two together until you have a smooth as silk graham puree. Put it in the fridge to chill.
  2. Combine the butter, powdered sugar, brown sugar, and salt in a small bowl and, using a spatula, briskly stir everything together until the mixture is smooth and fluffy.
  3. Stir in the chilled graham puree until the concoction is evenly mixed together.
  4. Use the frosting right away or store it in an airtight container int he fridge for up to 1 week. If you store it in the refrigerator, be sure to loosen it up before using, otherwise it will be impossible to spread. (I just loosened mine with a whisk before using.)
For the Graham Cracker Cake:
  1. Heat oven to 350F. Pan spray a quarter sheet pan and line it with parchment paper, or line the pan with a silicone baking mat.
  2. Combine the butter and sugar in the bowl of a stand mixer fitted with the paddle attachment and cream together on medium high for 2-3 minutes, until light and fluffy. Scrape down the sides of the bowl halfway through this process, and again at the end.
  3. Add the eggs, one at a time, beating on medium-high for 1 minute after each addition. After you add the last egg, scrape down the sides of the bowl, then beat on the high for 4 more minutes. Scrape down the sides of the bowl again.
  4. Combine the buttermilk, key lime juice, and oil and with the mixer on medium speed, stream them in very slowly. It should take you about 3 minutes to add these liquids. Scrape down the sides of the bowl, increase the mixer speed to medium high, and paddle for an additional 2 to 3 minutes, until the mixture is practically white, twice the size of your original fluffy butter/sugar mixture, and completely homogenous. Stop the mixer and scrape down the sides of the bowl.
  5. Whisk the cake flour, graham cracker crumbs, baking powder and salt in a bowl.
  6. With the mixer on a very low speed, Slowly add the dry ingredients and mix for 45 to 60 seconds, just until your batter comes together. Scrape down the sides of the bowl, and then mix on low for an additional 45 seconds to make sure no lumps of cake flour get left behind.
  7. Pour the cake batter into the sheet pan and, using a spatula, spread the batter in an even layer in the pan.
  8. Bake for 25-30 minutes, rotating the pan front to back halfway through baking. The cake will rise and puff, doubling in size, but will remain slightly buttery and dense. At 25 minutes, gently poke the edge of the cake with your finger. The cake should bounce back slightly and the center should no longer be jiggly. If it doesn't pass these tests, leave the cake in the oven for an additional 3-5 minutes.
  9. Let the cake cool in the pan or on a wire rack or, in a pinch, in the fridge or freezer (what I always do!) The cooled cake can be stored in the fridge, wrapped in plastic wrap, for up to 5 days.
To Assemble the Cake:
  1. Put a piece of parchment paper or a silicone baking mat on the counter. Invert the cake onto it and peel off the parchment or mat from the bottom of the cake. Use the cake ring to stamp out 2 rounds from the cake. These are the top 2 cake layers. The remaining cake "scraps" will come together to make the bottom layer.
Layer 1- the bottom:
  1. Clean the cake ring and place it in the center of a sheet pan lined with clean parchment or a silicone baking mat. Use 1 strip of acetate to line the inside of the cake ring.
  2. Put the cake scraps together inside the ring and use the back of your hand to tamp the scraps together into a flat, even layer.
  3. Dunk a pastry brunch into the key lime juice (or use a spoon) and give the cake a good, healthy bath of half the juice.
  4. Use the back of the spoon to spread one half of the liquid cheesecake in an even layer over the cake. If it feels thick, dollop it around and use the spoon to gently pull it to the edge of the cake layer.
  5. Sprinkle one quarter of the graham crumbs evenly over the frosting. Use the back of your hand to press them lightly into the frosting, anchoring them in place.
  6. Use the back of the spoon to spread half the key lime curd as evenly as possible over the crumbs.
Layer 2- the middle:
  1. With your index finger, gently tuck the second strip of acetate between the cake ring and the top 1/4 inch of the first strip of acetate, to make a ring of acetate 5/6 inches tall, high enough to support the height of the finished cake.
  2. Set a cake round on top of the curd (if one of your cake rounds is jankier than the other, use it here in the middle and save the best one for the top.) Repeat the layering: lime juice, liquid cheesecake, crumbs, curd.
Layer 3- the top
  1. Nestle the remaining cake round into the curd. Soak it with the remaining lime juice, and then cover the top of the cake with the graham buttercream. Give it volume and swirls, or do as we do and opt for a perfectly flat top. Garnish the frosting with the remaining graham crumbs.
  2. Wrap the top cake with plastic, transfer the sheet pan to the freezer and freeze for a minimum of 12 hours to set the cake and fillings. The cake will keep, wrapped in plastic, in the freezer for up to 2 weeks.
  3. At least 3 hours before you are ready to serve the cake, pull the sheet pan out of the freezer, and using your fingers and thumbs. Pop it out of the cake ring. Gently peel off the acetate and transfer the cake to a platter or cake stand. Let it defrost in the fridge for at least 3 hours. (Wrapped in plastic the cake can be refrigerated for up to 5 days.)
  4. Slice the cake into wedges and serve.

Notes

*It isn't easy squeezing so many of those little key limes, and if you run short, you can use regular lime juice for in the cake batter, saving the key lime juice for the curd, and cake soak, where it matters more!

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