Separate the egg whites from the yolks. Beat white egg with a hand mixer at a high speed until soft peaks. Gradually add sugar, about 2 tbsp at a time. Stirring after each addition until sugar is completely dissolved.
Gradually add egg yolk one at a time while mixing then add vanilla essence, all-purpose flour, cocoa powder, and baking powder. Beat until just combined.
Divide the batter into 3 parts, then pour the batter into a 21 cm x 11 cm rectangular tin.
Bake at 175° Celsius for 20-25 minutes.
After baking, let the cake cool in the tin.
In a small saucepan heat dark chocolate and ⅓ cup heavy cream until bubbles appear on the edge of the saucepan. Turn off the heat. Stir until well combined. Let it cool.
Beat the rest of the heavy cream with a hand mixer until hard peaks. Mix ⅓ of the whipping cream into the melted chocolate. Stir slowly.
Once mixed, add the rest of the whipping cream and stir until well combined. Refrigerate.
Remove the chocolate cake from the tin. Spread chocolate mousse between cake layers, on top, and sides of the cake. Use a bench scraper for smooth sides. Refrigerate for 3 hours.
Combine gelatine and water in a small bowl, and let it bloom.
In a medium saucepan, mix cocoa powder and sugar until mixed well, then add water and mix again, and lastly, add heavy cream then mix again until well combined.
Heat over medium heat. Keep stirring the glazed until boiling. Turn off the heat. Cool the glazed for about 3 minutes then add bloomed gelatin, and stir until the gelatine is dissolved and well combined. Strain the glaze to remove lumps and bubbles.
Cover the chocolate glazed with plastic wrap and press it directly onto the surface of the chocolate glazed to prevent it from forming a skin on the surface. Let it cool in a room temperature for 2 hours.
Place a rack on a tray to catch the excess glaze. Slide two knives under the cake, then transfer it to a tray. Pour the chocolate glaze onto a cake until the cake is covered with glaze.
Refrigerate again for 30 minutes. After 30 minutes, transfer again the cake to a platter. Slice the cake then decorate each slice with gold leaves. The chocolate cake glazed is ready to serve. Enjoy!