Salted caramel chocolate fudge "Giant" cake

I had the inspiration to bake another cake today, so I decided to try this recipe!

Before writing about the ingredients/instructions, I must say that I am always horrified by the amount of sugar and butter that goes into cake and icing. Making the pastry myself only makes me feel slightly better since I can control how much 'junk' goes into it @_@
Anyway, I'm calling this a giant cake because we didn't expect it to be so big.. (although the recipe did call for three layers). I only made 2 layers of cake because I got lazy, so please note the change in the buttercream proportions!

The instructions are a little long, but here goes:

Ingredients (for a three-layered cake)

Dark chocolate cake layers:

1. 2 3/4 cups all-purpose flour
2. 2 2/3 cups sugar (I used 1 cup white sugar + 1 cup brown sugar in mine)
3. 2 3/4 teaspoon baking soda
4. 2 3/4 teaspoon baking powder
5. 1 cup unsweetened Dutch-process cocoa powder (I used Hershey's)
6. 1 3/4 teaspoons salt
7. 0.6 cups vegetable oil 
8. 1 cup buttermilk (I made mine with fresh milk plus 1 tablespoon distilled white vinegar)
9. 4 eggs
10. 1 cup hot coffee 
11. 2 tablespoons of vanilla

Salted caramel Swiss meringue buttercream: (makes 2 layers of buttercream. During baking, I reduced everything to make only 60% of the original volume)

1. 1.35 cup castor sugar - separated into 0.85 cup and 1/2 cup portions
2. 1/4 cup water
3. 1/4 cup heavy cream at room temperature
4. generous pinch of sea salt (for the caramel, and additional sea salt, preferably Fleur de Sel, for sprinkling)
5. 5 large egg whites
6. pinch of salt (for meringue)
7. 2 tablespoons pure vanilla extract
8. 1.3 cups unsalted butter

Dark chocolate fudge frosting:

1. 1/4 cup + 2 tablespoons unsweetened Dutch-process cocoa powder (I used Hershey's)
2. 1/4 cup + 2 tablespoons boiling water
3. 1 1/2 cups/3 sticks unsalted butter at room temperature
4. 1/2 cup confectioners’/icing/powdered sugar, sifted
5. pinch of salt
6. 454 grams good-quality semi-sweet chocolate, melted and cooled (I used Ghiradelli semi-sweet chocolate chips)

Instructions:

For the cake layers: 

1. Preheat oven to 350°F
2. Grease and line 3 8-inch cake tins, dust with cocoa powder, tapping out the excess. 
3. In a large bowl, sift in all the dry ingredients. 
4. Add all the remaining ingredients to the bowl with the dry ingredients and mix well with a heavy hand whisk for about 2 minutes. 
5. Pour into prepared tins (batter will be quite liquid). Tap the tins on the counter a few times. 
6. Bake each layer for about 20-25 minutes, rotating once (if necessary). 
7. The cake is done when toothpick or skewer comes out barely clean. Refrain from overbaking. Cool completely on a wire rack in the pan.

Preparing the salted caramel Swiss meringue buttercream: 

Prepare the salted caramel first. 

1. Place 130 grams/5 ounces/1/2 cup + 2 tablespoons of the castor sugar and the water in a medium saucepan to a boil over medium heat. 
2. Stop stirring and cook until caramel is dark amber, gently swirling from time to time. 
3. Remove from heat, and gradually add the cream, whisking by hand until smooth. It will be splatter slightly (less if cream is room temperature). 
4. Whisk in sea salt and vanilla. Let cool and start the buttercream immediately.

To make the buttercream

1. Combine the egg whites, sugar and salt in a heatproof bowl over a pan of simmering water. 
2. Whisk frequently, keeping it over the heat, until the mixture reaches about 160°F and the sugar has dissolved. 
3. Transfer the mixture to a mixer with a whisk attached and beat on medium-high for 8 minutes, until stiff peaks have formed and the mixture has cooled to room temperature. 
4. Turn down the speed to medium and start adding small chunks of butter, checking that it has incorporated before adding more.
5. Keep beating until it comes together.  
6. With the mixer running on low, drizzle in the salted caramel sauce gradually, beating until well combined between each addition. 

Preparing the dark chocolate fudge frosting: 

1. Combine cocoa powder and the boiling water in a small bowl or glass measuring cup, and stir until it cocoa has dissolved. 
2. Beat the butter, the icing sugar, and salt on medium-high speed until it is pale and fluffy–about 5 minutes. 
3. Reduce mixer speed to low, and add melted chocolate (cooled), beating until combined and scraping down the sides of the bowl as needed. 
4. Beat in the cocoa mixture until well incorporated. 

Assembling the cake: 

1. Dollop a small bit of buttercream onto your intended serving plate/cake board. 
2. Place one cake layer on and layer on about 3/4 cup of the salted caramel buttercream. 
3. Repeat with the second layer of cake. 
4. Place the last layer of cake on top and coat the entire cake with a crumb coat using the chocolate fudge frosting. 
5. Refrigerate cake for 15-20 minutes. 
6. Once the crumb coat is set, remove cake and cover with the remaining fudge frosting. 
7. Return cake to the fridge and let it set, about 15-20 minutes. Sprinkle with fleur de sel or flaked sea salt to decorate.

Photo-time!

Here's how my cake batter looked like:

After combining both cake layers with a layer of salted caramel buttercream:

 It looks like a GIANT MACAROON. I flipped the bottom layer so that the flat part was contacting the buttercream

 Here you can see how much my top layer rose.

 After frosting with fudge!

It looks better after setting!

Taste test: the cake tasted a little too strongly of baking soda, so maybe next time I'll add slightly less of that. In general everything tasted nice, but the cake layer might have been a bit thick, though moist, relative to the buttercream (probably why the original recipe asked for 3 layers).