CAKEBRAIN’S BEST MINI CHOCOLATE MOUSSE LAYER CAKE

‘Tis the season to overindulge.

However, I have your waistlines in mind dear readers, with this fabulously decadent Chocolate Mousse Layer Cake recipe.  You can have your cake and eat it too as you’ll see.  It's all about portion control.  Instead of relying on sheer will power for portion control, the recipe has been downsized to a Mini version so that there isn't any more cake to eat even if you want it.  That is, unless you don't share like you're supposed to and end up eating the whole darned cake.

I have a small family of four and it’s a painful waste when I make a delicious regular-sized cake (9 or 10 inches) because there are always a few slices left over which become stale.  We get a tad sick of eating so much of the same cake.   I’ve been working hard to develop a recipe for a Mini Chocolate Mousse Layer cake that is simple to make, relatively quick and super chocolatey.  It also looks fancy enough to bring as a gift to a small dinner party (for 4 people...6 if they're not big eaters).

I think this recipe meets my needs and is my best so far.  Its sponge layers are moist but not too tender.  You need some structure (like a genoise) so that it can hold up the mousse filling and not dissolve into a soggy mess.   The cake layers do not need the finicky genoise technique and just require a stand mixer.   This cake is chocolatey but not overly rich or cloyingly sweet.  It employs quality dark chocolate and tastes somewhat like a soft truffle.   It doesn’t need frosting and comes out looking pretty smooth if you remember to use a spatula to smooth the top before allowing it to set in the refrigerator.  If you don’t do this, you can always cover the cake with chocolate shavings.  You can save a not-so-smooth cake by heating a metal spatula in really hot water, wiping it bone-dry and pressing it across the finished cake to smooth the surface a bit.  It works.  I did it.  Big gouges this technique won’t fix, but some little divots and bumps it will.

What is the most important thing to me about this cake is its size.  It’s Mini.   I used two 6-inch round pans to bake the cake layers.  Then I used a ring mold that is adjustable for the mousse component of the cake.  I adjusted the ring mold to about 7 inches…just enough to accommodate the cake layers with about a centimetre all around it for the mousse filling  (that’s a little less than a half inch to my American friends).  When the whole sponge cake recipe is made, it yields two 6-inch layers.  However, I chose to only use one of the layers…split in two…to make this particular cake.  I saved the other layer for a Chestnut Cream Cake using the same mousse technique.  That’ll be a later post.  That explains how you can have your cake…and eat it too.

If you wish, you could make one really tall chocolate mousse cake (love the height!), but I was afraid that my adjustable ring mold would not be high enough to accommodate 4 layers of cake and the alternating filling.  So.  Do just use one of the layers, split, and save the other layer for another recipe.  Or double the mousse recipe and make two mini chocolate mousse cakes.    The extra cake layer can be split, wrapped in plastic wrap and foil and then frozen for later use.
Click the jump to read the full recipe.

CAKEBRAIN’S MINI CHOCOLATE MOUSSE LAYER CAKE

I recommend weighing the ingredients for the cake layers in particular
Sponge Cake Layers (makes two 6-inch layers). 

• 60 g unbleached all-purpose flour [I used organic]
• 15 g cocoa powder [I used dark, dutch-processed Callebaut brand]
• 75 g sugar
• 4 large eggs, room temperature [I used free-range]
• 1 tsp melted unsalted butter

Cocoa Syrup

• 75 mL water
• 10 g cocoa powder
• 10 g sugar

Chocolate Mousse Filling

• 150 g dark chocolate, chopped [I used Callebaut, 70%]
• 300 mL whipping cream, cold
• 30 g confectioners sugar
• 5 mL pure vanilla extract
• 8 g powdered gelatine
• 30-45 mL water to bloom the gelatine

Decoration

• dark chocolate shavings or chocolate curls

Special Equipment:

• 2 6-inch/15.24 cm round cake pans [I used Wilton], lined with parchment circles and sprayed with Pam or Baking Spray
• 1 adjustable ring mold, or a 7 inch/17.78 cm metal springform pan

Preparation

1. Sift the flour and cocoa powder together in a bowl
2. Preheat oven to 180°C/ 356°F.  Have oven racks set in the middle
3. In a a small custard cup, soak the gelatine with the water until soft.  Place in microwave and “zap” it for 10 seconds.  Remove and stir until dissolved.  Continue to heat for a few seconds at a time until the gelatine is clear and not lumpy anymore.  You may need to add a few teaspoons of water to help this if you cannot get rid of the lumps.
4. Prepare in a small saucepan, the cocoa syrup.  Heat the sugar, cocoa powder and water until the sugar dissolves.  Stir well and allow to cool.

Sponge Cake Layers

1. Beat the eggs in a stand mixer with a whisk attachment until foamy.  Add the sugar and continue beating until pale and thick. 
2. Sift the flour and cocoa powder into the egg mixture.  Fold gently from the bottom up to avoid deflating the bubbles.  Add melted butter and fold well.
3. Equally distribute the batter between the two 6-inch cake pans.  Bake in a preheated 180°C/356°F oven for 15-20 minutes.  The cake will pull away slightly from the edges of the pan when you bring it out.
4. Turn the cake out while still hot.  Leave it to cool on a rack.

Chocolate Mousse Filling

1. In a double-boiler, melt the chocolate, stirring occasionally until smooth.   Add the bloomed gelatine to the melted chocolate and continue to stir over the heat until it is combined well with the chocolate.  Allow to cool
2. In a stand mixer with the whisk attachment, pour in the cold whipping cream, confectioner’s sugar and vanilla and whisk until soft peaks form.
3. Take a portion of the whipped cream with a hand whisk and lighten the chocolate mixture in a small bowl.  Then, pour the chocolate mixture into the bowl of whipped cream and fold with the whisk until combined.  Do not overmix.  Just gently incorporate until no white streaks appear.

ASSEMBLY

1. Split one sponge cake layer for this recipe.  Wrap the other one for another recipe.
2. Lightly brush the Cocoa Syrup on the split layers. 
3. On your serving platter or parchment-lined sheet pan, set the adjustable ring mold at 7 inches.  Centre one layer of the sponge cake in the middle, leaving a 1cm perimeter around the cake layer.  Pour half the chocolate mousse filling over the cake layer.  Use a small metal spatula to gently coax the filling around the perimeter of the cake so as to touch the sides of the mold.  You can gently tap the mold, holding it firmly down while doing so, to ensure that you do not get air pockets.
4. Gently place the second cake layer on the mousse filling and ensure it is in the centre of the mold.  Pour the rest of the mousse filling over this cake layer  ensuring that the mousse doesn’t leave air pockets around the perimeter of the cake layers.  Smooth the top.  Refrigerate until set.
5. To serve:  Remove the ring mold carefully using either a hot towel or hair dryer to heat the sides of the ring mold until the mousse is able to loosen easily from the mold.  Release the mold and carefully remove.  If you find little bumps on the sides, heat your small metal spatula in hot water, wipe bone-dry and use the heat of the spatula to smooth the bumps.  You can do this all around the edge of the cake to ensure a finished appearance.  This isn’t so important if you intend to decorate with chocolate shavings or curls.  Press the chocolate shavings into the sides of the cake and sprinkle generously over the top. 
6. Use a hot dry knife to cut slices of mousse cake.
7. You will not have left-overs.

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