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Dark Chocolate Mousse Cake

A combination of something rich, smooth, and indulgent. Enter the mousse cake. It’s like the dessert equivalent of a warm hug, especially when you layer dark chocolate mousse over a moist, fluffy chocolate cake.
Prep Time30 minutes
Cook Time2 hours
Course: Baking, Dessert
Cuisine: Vegetarian
Keyword: Bakery, chocolate, Coffee, eggless

Ingredients

for the cake:

  • 1 cup all purpose flour
  • ½ cup +1 tbsp sugar granulated
  • ⅛ cup + 1 tsp cocoa powder unsweetened
  • ¼ tsp baking soda heaped
  • ¼ tsp salt
  • ⅔ cup hot water
  • 4 tbsp olive oil
  • 2 tsp white vinegar
  • 1 tsp instant coffee granules
  • 1 tsp vanilla extract

for the sugar syrup:

  • ¼ cup sugar
  • ¾ cup water

for the dark chocolate mousse filling

  • 110 grams dark chocolate (preferably 70% cocoa)
  • 1 cup whipping cream
  • ½ tsp vanilla extract
  • 1 tbsp confectioners’ sugar
  • ¼ cup hot water
  • ⅛ cup cocoa powder

Instructions

for the cake

  • Pre-heat oven to 180 °C. Line the bottom of one 8 inch pan.
  • Whisk together flour, sugar, cocoa, baking soda & salt in a large mixing bowl. Do not use mixer.
  • Combine water, oil, vinegar, instant coffee & vanilla in a separate bowl.
  • Add to the dry ingredients & whisk till just combined. A few lumps are fine.
  • Pour batter into the prepared pan & bake for 20-25 mins till tooth pick inserted in center comes out clean.
  • Cool the cake in the pan on the rack for 15 minutes, then invert it on the rack. Leave it upside down to cool, it helps in flattening any dome shape.
  • I baked three layers by baking this recipe thrice separately. And then froze the layers wrapped in cling film.

for the sugar syrup

  • Boil water & sugar together. Once it boils, lower the flame & allow it to heat for another 1 minute. Remove from heat & cool completely. It can be made in advance & stored in refrigerator.

for the dark chocolate mousse filling

  • Start by whisking the hot water and cocoa powder together, then set it aside.
  • Melt the dark chocolate in a heatproof bowl over simmering water or in the microwave, and once it’s melted, let it cool slightly.
  • Now, pour the cocoa-water mixture into the chocolate and stir until it’s thick and smooth. Set this aside to cool.
  • Next, grab your mixer (either a hand mixer or stand mixer with the whisk attachment) and whip the heavy cream, powdered sugar, and vanilla on medium-high speed for about 3-4 minutes, until medium peaks form. You’ll know you’ve reached the sweet spot when the peaks hold their shape but still have a soft, airy texture.
  • Now, gently fold the chocolate mixture into the whipped cream using a spoon or rubber spatula. Be careful not to over-mix — we want the mousse to stay light and fluffy.
  • Cover the mousse and refrigerate it for at least 2 hours (or up to 2 days) to let it set. This will yield about 2 cups of velvety chocolate mousse, ready to be layered on your cake!

assembling the cake

  • Move the frozen layers to refrigerator few hours before assembling. Place the first layer on a platter or cake stand.
  • Make some holes into the bottom layer using a fork. Soak the bottom layer in sugar syrup. Then lightly spread chocolate mousse over it. Place the second layer on top of the bottom layer & repeat the process of soaking & spreading mousse. Finally place the top layer & again soak it. Lightly spread the mousse on top & sides of the cake.
  • Refrigerate the cake until mousse sets (about 1 hr). I refrigerated for 24 hrs prior to cutting covered in a cake dome as I wanted the flavors to really set in. Serve chilled.

Notes

  1. You can make a full recipe cake and then slice it into three layers or alternatively, you can bake 3 layers in separate pans by placing them in a big oven together.
  2. You can whip the ganache before spreading it as filling.
  3. The consistency of ganache for topping and filling is different. For filling, you need a thick consistency (which you get by leaving the ganache at room temperature for a few hours) and for pouring as a topping, you need the ganache to be pouring consistency. You can re-heat/ warm up the ganache to adjust the consistency.
  4. You can also prepare the mousse 1-2 days ahead of time
  5. How to Make the Best Mousse Cake
    Making a mousse cake may sound complicated, but trust me, it’s easier than it seems if you keep a few key tips in mind:
    • Perfecting the Mousse Texture: The texture of your mousse is crucial. The key to getting that light, airy mousse is whipping the cream (or egg whites) to soft peaks before folding them into the melted chocolate. Be gentle — the goal is to keep as much air in the mousse as possible to maintain that lightness.
    • Don’t Rush the Layers: To prevent the mousse from collapsing, give each layer some time to set in the fridge before adding the next one. It might take a little patience, but the results will be so worth it.
    • Avoid Common Mistakes: One mistake I see a lot is using chocolate that’s still too warm when folding it into the whipped cream. Allow the chocolate to cool slightly before mixing it in. This step is essential for a smooth, glossy mousse.