1. Preheat the oven to 180°C (350˚F). Grease a 23cm springform tin* and dust with some flour. Set aside. Chop the chocolate for the brownie.

2. Add the butter and chocolate to a small saucepan and heat up to melt both slowly. Add sugar and salt and stir until combined. Remove from the heat and let cool down for about 10 minutes. Add eggs and milk and mix until well combined. Sift the flour on top and fold in until just combined. Transfer the batter to the tin and smooth out the top. Bake for 22 minutes. The brownie should look slightly underbaked. Take it out of the oven and let it cool down completely. Grease the sides of the tin slightly and line with a clear acetate foil or a strip of baking parchment – you should get a height about 5cm higher than the edge of the baking tin. Set aside.

3. Separate the eggs for the filling. Add the egg whites to a large bowl and the egg yolks to a small one. Chop the chocolates and add to a large heatproof bowl. Melt the chocolate over a pot with simmering water. Take off the heat and let cool down a bit. Add the egg yolks to the cooled chocolate and mix until well combined. Set aside.

4. Add the gelatin leaves to a bowl with cold water and let soak for about 5-8 minutes. Add a bit more than 3/4 cup (200ml) of the heavy cream to a saucepan and heat up until bubbles come up on the sides. Remove from the heat. Squeeze the gelatin leaves to get rid of some water and add them to the saucepan – stir until completely dissolved. Set aside and let cool down for several minutes, then add to the bowl with the chocolate and mix in.

5. Add the remaining heavy cream to a large bowl ad whisk until stiff peaks form. Set aside.

6. Whisk the egg whites you added to another large bowl on high speed until foamy. Gradually add the sugar and continue whisking until stiff peaks form. The sugar should have dissolved completely (you can test by rubbing some of the mix between your fingers – if you can feel the sugar, you have to whisk a bit longer). Set aside.

7. Gradually add the whipped cream to the bowl with the chocolate mixture and carefully fold in. Do the same with the whisked egg whites – the goal is a creamy and fluffy chocolate mousse. Pour into the tin with the brownie base, smooth out the top and place in the fridge overnight. When ready to serve, remove from the tin, remove the foil or paper and place on a serving plate.