Soft tender lemon lime cake layers with a graham cracker crust, lemon lime curd filling, graham cracker crumble, and citrus cream cheese buttercream.
Ingredients
Lemon Lime Cake with Graham Cracker Crust
1cupbuttermilkroom temperature
4eggwhitesroom temperature
2/3 cup sour cream
1/3cup vegetable oil
1Tablespoon vanilla extract
2Tablespoons lemon & lime zest (so 1 T lemon , 1 T lime)
1/4cupfresh lemon/lime juice (1/8 cup lemon, 1/8 cup lime)
115.25ozWhite Cake MixI prefer Duncan Hines Brand for the best taste, but anything will be similar.
9wholegraham crackers
6Tablespoonsunsalted butter melted
Lemon Lime Curd
3eggyolks
1whole egg
1/2cuplemon/lime juice (1/4 cup lemon, 1/4 cup lime)
zestfrom one lime (about 1 teaspoon)
zest from one lemon (about 1 tablespoon)
3/4 cupgranulated sugar
4Tablespoonsunsalted butter
Citrus Cream Cheese Buttercream
2sticks (or 1 cup)unsalted butterleft out at room temp for 10 minutes or so
8ozcream cheese (or 1 brick)
pinch of salt
1Tablespoonvanilla extract
1teaspoon fine zest lemon/lime
1/8cupheavy cream
7-8cupspowdered sugar
Graham Cracker Crumble
9 whole graham crackers crumbled
Instructions
For the Cake Layers
Preheat the oven to 325 F (convection bake. If doing traditional bake, you'll just need to leave the cakes in a few minutes longer), and prep two 8" cake pans with a swipe of shortening and dust of flour to prevent sticking. Set aside.
In a food processor, pulse together the graham crackers and melted butter into a fine powder. Evenly distribute the crust between the two rounds and press firmly with the bottom of a measuring cup or glass. Set aside.
In a large bowl, hand-whisk the cake ingredients except for the cake mix. Sift in the cake mix and gently stir to combine (don't overmix). Split the cake batter between the two cake rounds and bake for 27-32 minutes until the center is completely baked through. Flip the cake rounds out onto a wire rack to cool completely, then wrap up in plastic wrap and freeze until assembly.
For the Curd
In a medium saucepan over medium heat, stir together the yolks, sugar, juice, and zest. Whisk together as the miture begins to thicken (about 3 minutes). After the curd thickens, remove from the heat and stir in the butter. Strain the curd and discard the zest. Cover the curd (directly) with plastic wrap on the surface and place in the fridge until it's completely cooled.
For the Buttercream
In the bowl of a stand mixer fitted with a paddle attachment, whip up the butter until it's light and fluffy. Add in the cream cheese and whip it up again until it's thoroughly combined.
Add in the salt, vanilla, zest, and heavy cream and combine.
Slowly add in the powdered sugar, about 1/2 cup at a time with the mixer on low speed, until it's all combined. If it's too thick, add in about 1 Tablespoon heavy cream if needed. If it's too thin, add in about 1/2 cup more of powdered sugar.
Flip on the speed to HIGH and whip for about 2 minutes to lighten color and volume.
Assembly
Place down the first cake layer with the graham cracker showing on top. Spread on a thin layer of buttercream with an offset icing spatula. Pipe a strong dam around the outside rim of the cake layer. Spread on about 1 1/2 cup of the lemon lime curd (don't overfill or it will leak out!). Place the next cake layer on top. Crumb coat the cake with a thin layer of buttercream and then freeze.
Add on a final thin coat of buttercream, press on the graham cracker crumbs on the side, then pipe a buttercream design on top using the Wilton 127 tip in a herringbone pattern (video is here for you to see how!) Enjoy!