Melt the Dark Chocolate and Butter together and set aside to cool down.
In a seperate bowl, whisk the Eggs and Brown Sugar until frothy. Sift in then stir the Plain Flour, Baking Powder and Salt.
Add the Melted Chocolate and Butter, then the Milk (optionally with 1 tbsp. Instant Coffee Powder melted in the milk). Quickly stir until combined, then pour into a round Springform Pan.
Bake for 15 to 20 minutes, or until the tip of a knife comes out clean. Set aside to cool down completely.
Chocolate Bavarois Cream
Place the Milk into a medium-size Pot and slowly heat it up. In the meantime, whisk the Egg Yolks and Sugar in a seperate heat-proof bowl.
When the milk starts to boil, directly remove from the heat. Pour it over the Egg Yolks and Sugar while constantly whisking. When combined, transfer back into the pot on the stove on low heat
When the cream starts to boil, add the Agar Agar Powder (see note 1 if using gelatine powder instead) and whisk for one minute before removing from the heat.
Add the thinly chopped Dark Chocolate to the hot cream and gently stir until fully melted (see note 2) then transfer into a clean bowl. Set aside to cool down.
Place your Heavy/Thickened Cream in the bowl of your mixer, and whisk until you achieve a stiff whipped cream.
Gently fold the Whipped Cream into the Chocolate Cream (see note 3) with a silicone spatula in 2 or 3 times. If the whipped cream seem to melt because your chocolate is still too warm, don't worry - it will set again in the fridge.
Pour the Chocolate Bavarian Cream over the Chocolate Brownie Base and place in the fridge to set for 3 hours at least. Keep in the fridge for up to 3 days.
Gelatine Powder can be used instead of Agar Agar Powder. The equivalent would be 2 1/2 teaspoon of Gelatine Powder dissolved in a little bit of Cold Water. Make the Creme Anglaise then remove from the heat. Add the Gelatine and whisk it into the hot cream until fully dissolved, then add the chopped chocolate. Leave it to cool down completely in the fridge, covered with wrap touching the surface of the cream, before folding in the whipped cream.
Make sure to add the chocolate away from the heat to avoid burning it. Chopping the chocolate allows it to melt much more quickly.
Agar will make the cream set very fast. If you see that the cream has started to set when you are ready to fold in the whipped cream, vigorously whisk it to loosen it up.
Recipe provided by "A Baking Journey" - https://www.abakingjourney.com