Sweet and Salty Cake
Baked, New Frontiers in Baking
Yield:  1 (8-inch cake)

For the Classic Chocolate Layers
3/4 cup unsweetened cocoa powder
1 1/4 cups hot water
2/3 cup sour cream
2 2/3 cups all-purpose flour
2 tsp. baking powder
1 tsp. baking soda
1/2 tsp. salt
3/4 cup (1 1/2 sticks) unsalted butter, softened
1/2 cup vegetable shortening
1 1/2 cups granulated sugar
1 cup firmly packed dark brown sugar
3 large eggs, at room temperature
1 tbsp. vanilla extract

For the Salted Caramel
1/2 cup heavy cream
1 tsp. fleur de sel
1 cup sugar
2 tbsp. light corn syrup
1/4 cup sour cream

For the Whipped Caramel Ganache Frosting
1 pound dark chocolate (60 to 70% cacao), chopped
1 1/2 cups heavy cream
1 cup sugar
2 tbsp. light corn syrup
2 cups (4 sticks) unsalted butter, soft but cool, cut into 1/2-inch pieces

To Assemble the Cake
2 tsp. fleur de sel, plus more for garnish

Make the Classic Chocolate Cake Layers
Preheat the oven to 325°F.  Butter three 8-inch round cake pans, line the bottoms with parchment paper, and butter the parchment.  Dust with flour, and knock out the excess flour.

In a medium bowl, combine the cocoa powder, hot water, and sour cream and set aside to cool.

Sift the flour, baking powder, baking soda, and salt together into a medium bowl and set aside.

In the bowl in an electric mixer fitted with the paddle attachment, beat the butter and shortening on medium speed until ribbonlike, about 5 minutes.  Add the sugars and beat until light and fluffy, about 5 minutes.  Add the eggs, one at a time, beating well after each addition, then add the vanilla and beat until incorporated.  Scrape down the bowl and mix again for 30 seconds.

Add the flour mixture, alternating with the cocoa mixture, in three additions, beginning and ending with the flour mixture.

Divide the batter among the prepared pans and smooth the tops.  Bake for 35 to 40 minutes, rotating halfway through the baking time, until a toothpick inserted in the center of each cake comes out clean.  Transfer the cakes to a wire rack and let cool for 20 minutes.  Invert the cakes on the rack, remove the pans, and let cool completely.

Make the Salted Caramel
In a small saucepan, combine the cream and fleur de sel.  Bring to a simmer over very low heat until the salt is dissolved.

Meanwhile, keeping a close on the cream mixture so it doesn’t burn, in a medium saucepan combine 1/4 cup water, the sugar, and corn syrup, stirring them together carefully so you don’t splash the sides of the pan.  Cook over high heat until and instant-read thermometer read 350°F, 6 to 8 minutes.  Remove from the heat and let cool for 1 minute.

Add the cream mixture to the sugar mixture.  Whisk in the sour cream.  Let the caramel cool to room temperature, then transfer to an airtight container and refrigerate until you are ready to assemble the cake.

Make the Whipped Caramel Ganache Frosting
Put the chocolate in a large heatproof bowl and set aside.

In a small saucepan, bring the cream to a simmer over very low heat.

Meanwhile, keeping a close on the cream mixture so it doesn’t burn, in a medium saucepan combine 1/4 cup water, the sugar, and corn syrup, stirring them together carefully so you don’t splash the sides of the pan.  Cook over high heat until and instant-read thermometer read 350°F, 6 to 8 minutes.  Remove from the heat and let cool for 1 minute.

Add the cream to the caramel and stir to combine.  Stir slowly for 2 minutes, then pour the caramel over the chocolate.  Let the caramel and chocolate sit for 1 minutes, then, starting in the center of the bowl, and working your way out to the edges, slowly stir the chocolate and caramel mixture in a circle until the chocolate is completely melted.  Let the mixture cool, then transfer it to the bowl of an electric mixer fitted with the paddle attachment.

Mix on low speed until the bowl feels cool to the touch.  Increase the speed to medium-high and gradually add the butter, beating until thoroughly incorporated.  Scrape down the bowl and beat on high speed until the mixture is fluffy.

Assemble the Cake
Place one cake layer on a serving platter.  Spread 1/4 cup of the caramel over the top.  Let the caramel soak into the cake, then spread 3/4 cup of the ganache frosting over the caramel.  Sprinkle 1 teaspoon of the fleur de sel over the frosting, then top with the second cake layer.  Spread with caramel, then the caramel frosting and sprinkle with 1 teaspoon of the fleur de sel.  Then top with the third layer.  Spread with caramel.  Crumb coat the cake and put the cake in the refrigerator for 15 minutes to firm up the frosting.  Frost the sides and top with the remaining frosting.  Garnish with a sprinkle of fleur de sel.

The cake will keep in a cake saver at room temperature (cool and humidity free) for up to 3 days.  If your room is not cool, place the cake in a cake saver and refrigerate for up to 3 days.  Remove the cake from the refrigerator and let it sit at room temperature for at least 2 hours before serving.