Place a heatproof bowl over a pot of boiling water.
Add chocolate, brandy, coffee and vanilla to the bowl.
Let it simmer in the double boiler until the chocolate is mostly melted. Take the bowl off the heat and give the mixture a whisk.
In a standing mixer fitted with a paddle attachment add 8 egg yolks and ½ cup sugar. Whip on high for about 4 minutes or until a light lemon color.
Slowly drizzle in the chocolate mixture on low.
Transfer to a large bowl.
Add a whisk attachment and a clean bowl to your standing mixer.
Add 1 cup egg whites, 1 ½ tbsp sugar and a pinch of salt.
Whip until stiff but not over whipped peaks.
Fold in ¼ of the whipped mixture to the chocolate mixture. Lightly whisk together.
Fold in the remaining whipped mixture to the chocolate until combined.
Put the egg white bowl back on the stand mixer fitted with a whisk attachment. Add 1/2 cup cream, 1 tbsp sugar and 1 tsp orange liqueur. Whip until peaks form.
Fold the whipped mixture into the chocolate mixture. This will give the mousse more structure and creaminess.
Give the mousse mixture a quick whisk.
Pour into serving cups. Chill for about 1-2 hours.
For the Whipped Cream:
Add 3/4 cup heavy cream, sugar and 1 tsp cointreau to a cold bowl. Whip on high.
For the Assembly:
Add a dollop of whipped cream to the top of each mousse cup.