Heat half of the cream in a medium saucepan, over medium-high heat until bubbles begin to form around the edges.

Place the chocolate and coffee into a large heatproof bowl. When the cream comes to the boil, pour it over the chocolate. Leave for a few minutes for the chocolate to start to melt, then whisk until the chocolate is completely melted and the mixture is smooth.Stir in the remaining half of the cream. (Adding this cold cream helps cool the mixture down faster).

Refrigerate until very well chilled - at least several hours or ideally overnight.If you’re in a hurry you can place the bowl in the freezer for 1 hour, stirring it every 10-15 minutes to make sure it doesn't freeze at the edges.

Once the mousse mix is fully chilled, whip it with an electric hand mixer until stiff peaks form. If it seems like it's still a little too soft to pipe, you can refrigerate the bowl of mousse again for 10 minutes or so until it firms up some more.

Transfer the mixture to a piping bag fitted with a large star or round piping tip and pipe it into serving glasses or bowls. You can also just spoon the mousse into the glasses if you prefer.

Put the instant coffee, caster sugar and boiling water into a bowl. Whip with an electric mixer (or use a hand whisk and a strong arm) until thick and foamy, and much lighter in colour.

Put the cream, sugar and vanilla into a bowl and whip with an electric mixer until thickened, and soft peaks form when you lift up the mixer.

Spoon the toppings onto each of the mousses. I found it handy to use an ice cream scoop, but a spoon will do the job just fine too.To dust the whipped cream with chocolate, sift together the cocoa powder and powdered sugar, then sift or dust it over the whipped cream.

Serve the mousse immediately, or store, covered or in an airtight container, in the fridge.The mousse will keep well for several days, but the whipped coffee topping looks its best for up to a day, and then it will start to slowly deflate. It still tastes the same, it just doesn't look so pretty.