Lemon Lime Layer Cake with Raspberry Crumble Filling
My friend requested his birthday cake be a combination of all his favorite flavors.... Lemon meringue, key lime pie, raspberries and a good old fashioned vanilla cake. Upon his request, the wheels started turning as to how I would put this together. Or more so, HOW HIGH COULD I SAFELY STACK THIS CAKE? This recipe ain't for the faint of heart, it's a multi-stepper (it turned into a multi-dayer!), but worth it! Get creative, change it up, send me your variations so I can try them too :)
I started out by baking a simple white cake, putting half of the batter into 2, 8" round pans. I didn't get crazy reinventing the wheel, I used my favorite recipe, from Martha Stewart. I baked the cakes the night before so they had time to fully cool. I get all excited when I'm baking and want to start assembling while piece are still warm, and it causes a slippy slidey disaster.
The next step was to prepare the lemon curd, and let it have the night in the fridge. I'm not sure why, but I think lemon curd tastes even better if you let it sit overnight (is it possible to make it any better?).
- 1/4 cup loosely packed lemon zest (1-2 lemons)
- Juice from 1-2 large lemons
- 4 egg yolks
- 1/2 cup white sugar
- Pinch of salt
- 6 TBSP room temperature butter
Toss all of your ingredients into a pot, aside from the butter. Place the pot into another pot with about 1" of "on the verge of boiling" water. Don't let the double boiler setup actually boil, or you will accidentally make scrambled eggs! Stirring constantly with a whisk or fork, keep those ingredients moving. I hold it in a hover position over the boiling pot, never letting it rest just to be safe. Can take anywhere from 10-20 minutes depending on your temperatures. Your curd will start to form, and thicken. When you're happy with the texture, remove from heat. Stir in 1 TBSP of butter at a time until each is fully melted. Place fine mesh strainer over bowl, and force curd through with a soft spatula, leaving the lemon zest behind. Cover with plastic wrap, pressing the plastic wrap onto the surface of the curd to stop it from forming a film on top. Refrigerate overnight.
The next morning was a Saturday, I got up at 6am to start the assembly! I have a trick so I can run the food processor and the Kitchen Aid mixer at the wee hours of the morn' without my husband hollering at me.... I turn on a really noisy fan in the bedroom and let the white noise drowned out my mad one-man baking parties in the kitchen one floor away.
The last two flavors I wanted to capture were raspberry and keylime. I debated if I should try baking a key lime pie and stacking it in there (too heavy I figured), or make some keylime ball of sorts (should have baked them into the cake I decided, too late). So I settled on a keylime butter cream frosting to be used as a gluing layer, and I'd take the graham cracker crust goodness, and turn it into a raspberry riddled crumble layer instead. Next step was to make the butter cream frosting.
Keylime Butter Cream Frosting
- 1 cup room temperature butter
- 2 cups powdered sugar
- Zest from one lime
- Juice from one lime
- 1/4 cup condensed milk
Place butter in bowl of standing mixer. Using whisk attachment, whisk on medium until fluffy. Add in zest and juice. Slowly sift in sugar. Add in condensed milk and whisk on high for another 2 minutes. Take 1/4 cup of this mixture and place in a small bowl. Put the rest in a covered bowl and leave on the counter so it's soft for assembly. Take about another 1/4 cup of condensed milk, and mix it into the reserved 1/4 cup of frosting. Add in more lime zest and juice to taste. Leave this on the counter so it's nice and fluid, we will drizzle the cake in this at the end of construction; if it's too stiff, add more lime juice.
Raspberry Graham Cracker Crumble
- 1 cup graham cracker crumbs
- 1/2 cup sugar
- 1/3 cup melted butter
- 1 cup raspberries in syrup, thawed and lightly drained
Mix graham cracker crumbs and sugar in a bowl. Add in melted butter and stir until fully coated. Add in preserved raspberries in syrup (from the frozen fruit section), but ensure they are fully thawed before mixing in. No need to pour off all of the syrup, just strain them with a spoon as you measure them out. Gently fold them into the mix until fully incorporated. Set aside in fridge.
Now it's time for assembly! Find yourself a nice big serving platter, cause this one is messy, and heavy. Place one white cake round onto the platter. Smear with a coat of butter cream frosting, using about half. I like to push the cream to the edge of the cake so it shows oozing out of the layers. Next, pour entire contents of lemon curd into the center. Spread evenly to the edge. Next, add your raspberry crumble layers, saving about 1/4 cup for decoration at the end. Pack down tightly using fingers. Next, take the remaining white cake and turn it upside down onto a plate. Smear the bottom side with the remaining butter cream. Now it's time to flip the cake on top of the stack! This is scary, careful not to break the cake in half. Do it quick, in one swift motion. Don't worry, the finished cake has a really rustic look, so imperfection is A-ok. Once your top cake is on, it's time to garnish! Take the reserved keylime butter cream that you loosened with condensed milk and pour into center of the cake. Allow it to roll and drizzle over the edges. Next, sprinkle with raspberry crumble mixture. Take a few of the remaining raspberries in syrup and drizzle over the top. Finish with a twist of lemon or lime. Clean the edges of your plate so it looks pro, yo! VOILA! I placed mine in the fridge covered for about 6 hours before serving to make sure it was all tightly leveled and stable. It turned out looking like the ULTIMATE pancake, and tasting like all of the requested flavors, married just right. Then, I called my friend's who's bday it happened to be, had him come over, we stared at the cake for 30 seconds, then, we ate it. DELISH!