1. In a bain marie melt the chocolate then add the espresso. Mix it together until completely smooth, turn off the heat and keep it aside.
2. Now, turn off the heat add the butter, powdered chilli and egg yolks. Mix it together until smooth and then leave it to cool a bit.
3. In a bowl beat two egg whites with a pinch of salt, once the whites become foamy, add the powdered sugar and continue to beat for another few minutes.
4. Mix the egg whites with the chocolate mixture, little at a time; you should have a cream that's light and foamy.
5. Place the mousse into the ramekins and let it rest in the fridge for 3 to 4 hours.
6. Serve the mousse chilled along with whipped cream.