Mint Chocolate 'Aero' Cake

A gigantic chocolate cake is a really nice thing to come home to. Even if it's one that's been thrown together quickly, or one that's taken a days preparation, it's so good when you can dig into a big slice of that gooey, rich homemade goodness. I'd been playing with the idea of making a Mint Chocolate themed dessert for a while, something that reminded me of one of my favourite candy bars; mint Aero. Ever since I saw this great idea for a 'bubble-wrap mousse' from Taste, I knew I wanted to adapt it for my mint Aero dessert. I experiment a little-had a slight failure with small cups of green mint & white chocolate mousse topped with maltesers, and decided it wasn't pretty enough. Eventually I decided it needed to be a giant, four-layered chocolate cake, reminiscent of the triple-triple chocolate cake which was an undeniable hit.

So it seemed simple enough, I baked up my usual chocolate cake recipe, and used the Taste recipe for the white chocolate mousse and added a bit of peppermint. After a day of chilling, I was ready to put everything together. The cakes were neatly sliced up into 4 layers, and I started to sandwich the mousse in between them. And then all hell broke loose. In hindsight, I really should have known better. The mousse recipe was never really meant to be used inside a cake. It started turning into mint chocolate SOUP, and started oozing out the sides and soaking into the cake, making the layers collapse around the edges. I really should have used a much more well-set mousse that used gelatine or something. So much fail was going on in my kitchen. I was certain if I waited any longer to do something the top half of the cake was going to slide right off the stand.

It was tempting to throw the towel in, as I frantically scooped up the leaky mint chocolate soup of the cake by the handful. At this point I said, "F*** it, I did a night's worth of prep baking and used up all these ingredients, I'm going to turn this into an edible cake even if it friggin' kills me!". So I whipped up a batch of dark chocolate ganache. It's a good philosophy for the kitchen; if there's a problem, throw some ganache at it. And so my ugly fail cake was hidden under a thick layer of luscious chocolate ganache.

Somehow, the cake did not collapse under it's own weight. By the time I was putting the ganache on, I was extremely cranky and swearing loud enough for my neighbours to hear, so I didn't even bother trying to make it smooth. And then while topping it off with Lindt chocolate balls (as inspired by the Taste recipe) I realised I didn't have enough of the chocolates and had to run down to Coles for more. I hate when that happens. And when I woke up this morning to take photos, it was pitch black. I HATE WHEN THAT HAPPENS. So my day was deprived of chocolate cake, but at least I had something to look forward to when I got home. I cut a slice out of the cake, dreading the mess that was hidden inside...yeah...the lovely flavoured bright green filling had pretty much disappeared and the cake was a little denser than usual, but it still tasted great. And I still love the idea, which is why I'm posting the recipe. I will just never ever use that mousse as the filling again, EVER.

Mint Chocolate 'Aero' Cake
(adapted from Ina Garten's Beatty's Chocolate Cake recipe, serves 10-12)
Butter, for greasing the pans
275g (1 3/4 US cups) plain flour, plus more for pans
500g (2 US cups) sugar
75g (3/4 US cups) good cocoa powder
2 teaspoons baking soda
1 teaspoon baking powder
1 teaspoon salt
240ml buttermilk, shaken
120ml vegetable oil
2 extra-large eggs, at room temperature
1 teaspoon pure vanilla extract
1 cup freshly brewed hot coffee

For the mint chocolate mousse filling:
I am not including the recipe I used because it was completely inappropriate for this cake. I'd recommend a gelatine based mousse (maybe like this one), a mint buttercream or adapt the dark chocolate ganache recipe below using white chocolate + peppermint essence & green food colouring

Preheat the oven to 180 degrees C. Butter 2 19cm round cake tins. Line with parchment paper, then butter and flour the pans.

Sift the flour, sugar, cocoa, baking soda, baking powder, and salt into the bowl of an electric mixer fitted with a paddle attachment and mix on low speed until combined. In another bowl, combine the buttermilk, oil, eggs, and vanilla. With the mixer on low speed, slowly add the wet ingredients to the dry.

With mixer still on low, add the coffee and stir just to combine, scraping the bottom of the bowl with a rubber spatula. Pour the batter into the prepared tins and bake for 35 to 40 minutes, until a cake tester comes out clean. Cool in the tins for 30 minutes, then turn them out onto a cooling rack and cool completely. Wrap in cling film and chill for at least 3 hours or overnight. If making a mint chocolate mousse for the filling, prepare this and chill for at least 3 hours or overnight.

For the chocolate ganache:
450g (approx 1 pound) dark chocolate (I used 70% cocoa Lindt)
600ml (2 1/2 cups) pouring cream
Optional: 3x150g boxes of Lindt chocolates to decorate

Break up chocolate into small pieces and place in a large mixing bowl. Slowly bring cream to just to the boil in a medium saucepan. Remove from the heat and cool for a couple minutes. Pour hot cream over chocolate and set aside to cool for 10 minutes. Mix cream and chocolate together until smooth using a whisk, then cool until it reaches room temperature. Using an electric mixer, beat mixture until it is shiny, fluffy and just holds its shape (take care not to overmix or mixture will split, remelt and rebeat mixture if this happens).

When ready to assemble, use a long serrated knife to slice your two cakes into half (or leave them as two thicker layers if you wish). Sandwich cake layers with a layer of green mint chocolate filling. Crumb coat the outside of your cake with dark chocolate ganache, then use the rest of the ganache to ice your cake. Make sure to work quickly or ganache will set. Decorate top of cake with Lindt chocolates. Chill for at least an hour before serving, run a knife under hot water before slicing up.