Base: Lightly grease the bottom and sides of a 20cm (8inch) springform pan.
Crush the biscuits with a rolling pin or blitz in a food processor.
Melt the butter and add to a medium bowl with the crumbs and stir to combine. Pour the mix into your prepared pan, pressing it firmly down and level with a spatula. Place it in the freezer or fridge to chill, while you prepare the filling.
Cheesecake filling: Melt the chocolate in a heatproof bowl over a pan of simmering water (double boiler method), making sure it doesn’t touch the water.
Stir in the espresso powder and then set aside until needed.
Using an electric hand mixer or food processor, beat together the cream cheese and sugar until smooth. Then pour in the cream, whisking continuously, until thick and smooth.
Add the cooled chocolate and whisk vigorously until combined, scraping down the sides of the bowl as necessary. Pour the mixture over the biscuit base, smoothing it out with a spatula. Chill in the fridge for at least 4 hours, until set.
Chocolate Ganache: In a small saucepan, combine the cream and 1-2 tsp of instant coffee (depending on taste). Bring to a boil over medium-high heat.
Meanwhile chop the chocolate into small pieces and place in an heat proof bowl.Just as the cream comes to a boil, remove from heat and stir in the butter. Pour the cream over the chopped chocolate and let stand for 1 minute to melt the chocolate. Whisk until smooth, then pour just under half over the chilled cheesecake. Then place both the cheesecake and the ganache back in the fridge so it can thicken.
When the ganache has thickened, use an electric hand whisk to aerate it. Then place it into a piping bag fitted with a star nozzle and pipe in a circular motion around the edge of the cake.
Decoration: Decorate with espresso beans and chocolate curls or shavings. To make chocolate shavings, freeze half a bar of chocolate (50g) and then grate it on a course grater.