• It is important to use a SPRINGFORM pan throughout this recipe. Another option is to bake a cake and use adjustable cake rings to build up the mousse.
• I have used a 9” round springform pan here.
• Prepare the cake as per the recipe and instructions here.
• Let it cool down completely before adding the mousse.
• I like to prepare it a day ahead of time and store it wrapped in plastic wrap and foil. Leave it in the fridge or at room temperature until layered with mousse.

Preparing the cake pan for layering

• Slice the top of the cake horizontally to level it flat and then add the mousse layer.
• You can choose to keep a thin layer of cake by slicing it accordingly.
• Enjoy the scrapes with tea or coffee or maybe make some cake pops.
• Try using an acetate or parchment paper collar on the circumference of the inner side of the pan for smooth removal of cake later.

Prepare Semi-sweet chocolate mousse

Process of melting chocolate

• Warm-up cream in a microwave-safe bowl or in a pot over a stovetop just until a simmer and not boiling hot.
• Add in the semi-sweet chocolate chips and cover the bowl with a lid/ dish. Keep it undisturbed for 30 seconds. The trapped heat of the cream will slowly start to melt the chocolate.
• Now open the lid and start stirring gently. It will look goopy at first but after a minute of stirring it will start to form a smooth chocolate sauce known as ganache.
• If you suspect that all the chocolate didn’t melt then just pop it in the microwave for 10 seconds at a time. Smoothen out the tiny bits of chocolate and keep the ganache aside to cool at room temperature.

Whipping chilled heavy whipping cream

• Meanwhile in a big bowl add cream, a pinch of salt, and vanilla. Whip it with an electric or handheld whisk for 4-5 minutes. Or until you see that the cream has started to just thicken. Now switch off the electric whisk and just manually whisk it to a super soft consistency. Whisking with a hand, later on, gives you more control over the consistency and avoids over-whipping the cream.
• We are looking for a very soft peak consistency. Refer to the video for better understanding. Please do not whisk until stiff peaks. The cream should be just thick and not hold the peaks at all.

Mixing process to make the mousse

• The chocolate should have come to room temperature by now. It should not be warm.
• Now scoop 3-4 tablespoons already whipped cream into chocolate first. Fold it gently so that the cream is completely incorporated with chocolate. This is done to stabilize chocolate. It is a crucial step taken to avoid chocolate seizing when it comes in contact with chilled cream.
• The next step is adding the chocolate mixture to the big bowl of already whipped cream. Fold it gently in one clockwise direction. We want the mouse light and fluffy. This way we are incorporating air in the mousse.
• Once it is mixed well, add it to the prepared cake pan. Level the top with a spatula as much as you can. It does not have to be perfect. Loosely cover it with foil and chill in the refrigerator (not the freezer).

Prepare White Chocolate Mousse

• Important - Follow the sequence – 1st whip the cream and set it aside. 2nd – activate the agar-agar. 3 rd – Melt the white chocolate. You can do the 2nd and 3rd steps simultaneously using two stove-top.

Whip heavy whipping cream

• Same as you would do for semi-sweet chocolate mousse. Just repeat the process.
• In a big bowl add cream, a pinch of salt, and vanilla. Whip it with an electric or handheld whisk for 4-5 minutes. Or until you see that the cream has started to thicken. Now switch off the electric whisk and just manually whisk it to a super soft consistency. Whisking with a hand, later on, gives you more control over the consistency and avoids over-whipping the cream.
• We are looking for a very soft peak consistency. Refer to the video for better understanding. Please do not whisk until stiff peaks. The cream should be just thick and not hold the peaks at all.

Activate agar agar

• Add agar-agar to a bowl of cream. Mix well to combine. Heat this mixture on medium heat stirring frequently. Once the mixture comes to a boil let it cook for a minute. Switch off the flame and let it cool to warm.

Make the white chocolate ganache

• I recommend using the double boiler method to melt white chocolate and not the microwave. White chocolate is very delicate and tends to burn in the microwave.
• Melt the cream and white chocolate using the double boiler method over the stovetop.
• Once it is silky smooth take the bowl off the stove and let the chocolate cool completely. The white chocolate will thicken as it cools but it should still be flowy consistency.

Make the mousse - Work quickly

• Now place the chilled whipped cream, agar-agar mixture, and white chocolate on your work table.
• Then scoop 3-4 tablespoons already whipped cream into the white chocolate first. Fold it gently so that the cream is completely incorporated with chocolate. This is done to stabilize chocolate. It is a crucial step taken to avoid chocolate seizing when it comes in contact with chilled cream.
• If you think chocolate is turning gritty then just add some more cream, it will turn smooth again.
• The next step is adding the white chocolate mixture to the big bowl of already whipped cream. Fold it gently in one clockwise direction until mixed, say for 20 seconds.
• Now add in the agar agar mixture. Make sure it is warm and flowy. It should not set before mixing. If you suspect that the mix is thickened, set, or cooled before adding it to the cream then warm it again on low heat until flowy consistency.
• The next step is to work quickly. Immediately add the agar cream mixture into the white chocolate whipped cream mixture and whip for 10-15 seconds, making sure it is blended well. Do not overwhip.
• Pour it over the semi-sweet mousse layer. Level as much as you can. Place it in the fridge to set for at least an hour before you layer it with ganache.

Making top ganache layer (Optional)

• Place semi-sweet chocolate in a medium-sized bowl. Warm-up cream in a microwave-safe bowl or in a pot over a stovetop just until a simmer and not boiling hot.
• Pour it over the chocolate chips and cover the bowl with a lid/ dish. Keep it undisturbed for 30 seconds. The trapped heat of the cream will slowly start to melt the chocolate.
• Now open the lid and start stirring gently. It will look goopy at first but after a minute of stirring it will start to form a smooth chocolate sauce known as ganache.
• If you suspect that all the chocolate didn’t melt then just pop it in the microwave for 10 seconds at a time. Smoothen out the tiny bits of chocolate and keep the ganache aside to cool at room temperature.

Assembling the cake and garnish

• Once the ganache has cooled down pour it over the white chocolate layer and swirl it to cover the top of the cake. Place it in the fridge to set overnight or at least 8 hours before garnishing.
• You may add some chocolate shards, shavings, curls, and berries to decorate the cake.