Sweet & Salty Millionaire's Layer Cake

I've had this incredible cake bookmarked for a very long time from Sweetapolita. I figured my birthday was the perfect time to try this rather involved recipe. None of the steps alone are overly complicated, but you end up making 3 layer cakes, shortbread crumbles, salted caramel, Swiss meringue buttercream and chocolate ganache. You can see why it takes quite a bit of time ... and butter. Lots of butter.

This was my first time making Swiss meringue buttercream, and I'm so glad I made it. It's a luscious, buttery frosting, that is very different than a typical buttercream. It will not become my standard, but it's a nice varietal to have in my frosting arsenal.

This is rich, decadent and lives up to its Millionaire name.

Sweet & Salty Millionaire's Layer Cake
Chocolate Cake
2 1/4 cups flour
2 1/4 cups superfine sugar
3/4 cup dark Dutch-process cocoa powder
2 1/4 tsp. baking soda
2 1/4 tsp. baking powder
1 tsp. salt
1 cup buttermilk
3/4 cup hot water
1/3 cup vegetable oil
3 eggs, room temperature
1 Tbsp. vanilla

Vanilla Bean Swiss Meringue Buttercream

6 egg whites
1 3/4 cups sugar
2 cups butter, softened, cut into cubes
2 tsp. vanilla bean paste
Pinch of salt

Salted Caramel

2 cups sugar
1/2 cup water
1 cup heavy cream
2 Tbsp. butter
2 tsp. vanilla or vanilla bean paste
Generous pinch of sea salt

Shortbread Crumbs

1 cup flour
1/4 cup sugar
1/2 cup butter, softened, cut into cubes

Ganache Frosting

1 pound plus 6 ounces dark chocolate, chopped
2 cups heavy cream
1/3 cup corn syrup
1/4 tsp. sea salt
1/2 cup butter, cut into cubes
1 Tbsp. pure vanilla extract

To make the cakes, preheat oven to 350° F. Spray three 8-inch round cake pans with cooking spray, and line the bottoms with parchment paper rounds. (If you have to bake each cake separately, the batter will be fine to do this.)

In the bowl of electric mixer fitted with the whisk attachment, sift together flour, sugar, cocoa powder, baking soda, baking powder and salt. In a large measuring cup with a spout, combine the buttermilk, hot water, oil, eggs and vanilla.

Add liquid mixture to dry ingredients, and mix on medium speed until smooth, about 1 minute. Divide batter among the 3 cake pans (weigh batter for even layers at about 520 grams per cake pan).
Bake 2 of the layers until a toothpick or skewer inserted into the center comes out with a few crumbs, about 20-25 minutes. Repeat with the final layer. Let cakes cool in the pans for 10 minutes, and then turn onto a wire rack until completely cool.

To make the Swiss meringue buttercream, wipe the bowl and whisk of an electric mixer with paper towel and lemon juice, to remove any trace of grease. Add egg whites and sugar, and simmer over a pot of water (not boiling), whisking constantly but gently, until temperature reaches 130°F, or if you don't have a candy thermometer, until the sugar has completely dissolved and the egg whites are hot, about 8-10 minutes.

Place bowl back on mixer, and fit with the whisk attachment. Whip on medium-high speed until the meringue is thick, glossy, and the bottom of the bowl feels neutral to the touch. (This can take up to 10 minutes, or longer). Switch over to paddle attachment, and with mixer on low speed, add softened butter in chunks until incorporated, and mix until it has reached a silky smooth texture. (If it curdles, keep mixing, and it will come back to smooth). Increase speed to medium, and beat until the mixture becomes thick and fluffy, about 2 minutes.

Add vanilla bean paste and salt, continuing to beat on low speed until well combined. Keep in an airtight container at room temperature for up to 1 day, refrigerated for up to 1 week, or in the freezer for up to 2 months. Thaw at room temperature. Bring chilled buttercream back to smooth consistency by bringing to room temperature and then beating on low speed with an electric mixer for a few minutes. (I had a hard time getting mine back to the same fluffy consistency, but I think I didn't have it warmed to room temperature, which might have been my issue.)

To make the caramel, n a medium saucepan over medium heat, stir the sugar and water until combined. Brush down the sides of the saucepan with a wet pastry brush, and increase the heat to medium-high. Stop stirring, and let the mixture bubble until it reaches an amber colour (about 350°F). Promptly remove the saucepan from the heat, and whisk in the heavy cream carefully until smooth, followed by the butter.

Clip a candy thermometer onto the saucepan, and return the mixture to medium-high heat until it reaches 248°F). Transfer the caramel to the heatproof bowl, and stir in the vanilla and sea salt. As the caramel reaches room temperature, it will become thick and spreadable. Store in a sealed jar in refrigerator for up to 2 weeks.

To make the shortbread crumbles, preheat oven to 350°F. Line a baking sheet with parchment paper or a Silpat mat. In a medium bowl, combine the flour and sugar. Cut in the butter using a pastry blender or your fingers, until you have distributed the butter and achieved pea-size bits. Turn the mixture in an even layer onto the prepared baking sheet, and bake for 10 minutes. Remove the tray from the oven and, using a heatproof spatula, gently break up the mixture and return to the oven for 10 more minutes. Let tray cool completely on a wire rack. Once cool, keep in an airtight container for up to 2 weeks.

For the ganache frosting, place chopped chocolate in a large heatproof mixing bowl. In a medium saucepan over medium heat, combine the cream, corn syrup and salt, and bring just to a boil. Pour hot cream mixture over the chocolate, and let sit for about 1 minute. Using a whisk, combine the chocolate mixture until smooth. Add butter and vanilla, and mix again until smooth. Mixture will thicken to spreadable frosting consistency, and eventually become solid at room temperature. To soften, simply warm and bring to desired consistency.

Prepare your fillings and frosting and ensure they are all at spreadable consistency. For the ganache, this will take about 15-30 minutes after making it, and about 30-60 minutes for the caramel. If you have made ahead, simply warm the ganache and let cool until spreadable, and do the same for the caramel.

Slice all three cake layers in half horizontally, so you have a total of 6 cake layers. Smear a small dollop of the ganache frosting on a cake plate, pedestal or cake board, and place your first layer cut side up (so bottom of the cake layer is touching plate), and using a small offset palette knife, spread about 1 cup of buttercream on the layer leaving about 1-inch around the edge, followed by one-third of the caramel and then a generous handful of shortbread crumble. Place your next cake layer on top, and spread about 1 cup of the ganache frosting all the way to the edge.

Repeat previous step until you get to the final cake layer. Place last layer face down (cut side down) and frost entire cake with the ganache frosting. Let sit for about 15 minutes and then finish with a thick coat of ganache frosting. Sprinkle on some Fleur de Sel. Finished cake can be kept at room temperature for up to 8 hours. Keep refrigerated if longer than 8 hours, but serve at room temperature.