Break the chocolate into a heat-safe bowl.

Pour 1 cup (240g) of heavy cream into a saucepan, and heat over medium flame until the cream just starts to simmer (bubble around the edges).

Pour the hot cream over the chocolate, making sure it covers all of the chocolate. Cover the bowl with a lid / plate and wait 2-3 minutes (you can whip the cream in the meanwhile).

After 5 minutes, gently stir with a spoon until the chocolate melts and combines with the cream, resulting in a smooth and shiny ganache. If there is any unmelted chocolate, microwave the ganache for 10-15 seconds until all the chocolate has melted. Let the ganache rest for 5 minutes.

Add the remaining 1 ½ cup (360g) cream to a large bowl. This cream must be straight from the fridge and chilled!

Use an electric hand mixer to whisk the cream for a few minutes until it reaches soft / medium peaks. This means the cream will thicken up and form 'ribbons' behind the mixer attachments, and when you turn off the mixer and lift it, the cream will form a soft peak which slowly falls back down. Essentially, the cream should be thick and hold shape partially, but not fully. Stop whisking immediately at this stage.

Add about a third of the whipped cream into the ganache (which should not be hot at this point), and use a rubber spatula to very gently and very slowly fold it in. Be extra gentle, and stop when they are mostly combined.

Add the whole mixture into the remaining whipped cream, and continue to gently and slowly fold. You want to fully mix the two without knocking out the air in the cream. If you see any lumps of whipped cream, press down on them with your spatula to break them. Stop mixing as soon as the cream has fully mixed with the ganache. You should have a smooth and fluffy chocolate mousse.

Divide the mousse evenly between the dessert cups (or serving dish of your choice). Refrigerate for at least 3 hours or until the mousse feels set.

Optionally, decorate with more whipped cream and grated chocolate. Serve and enjoy!