Pour ¾ cup of the whipping cream to a metal bowl and put it in the fridge along with the whisk to chill. Cold cream in cold utensils whips better.
Chop the chocolate. I use a mixture of semi-sweet and dark chocolate. Add it to a microwave-safe bowl along with ¼ cup cream. Microwave for 30 seconds and stir. Keep microwaving in 30-second intervals while mixing in between until melted. Put this chocolate ganache aside to cool.
Whip the chilled cream till medium peaks form.
Add the powdered sugar to the cream and beat once more to combine it.
Reserve 2-3 tablespoon of the cream for garnish.
Fold in the chocolate ganache into the whipped cream 3 batches with a spatula. Be patient while folding. You don't want to deflate the cream.
When everything is mixed in, pour this mousse into a piping bag. You can also spoon it into your ramekins or glasses. The piping bags makes it less messy though.
Refrigerate for an hour at least.
Before serving, top with some whipped cream, dust with cocoa powder, add sliced strawberries and a sprig of mint.