Start off by sprinkling the crushed biscuits all over the base of the tin.
Next break the chocolate into sections and put them in a heat proof bowl together with the liquid glucose and the rum. Sit over a saucepan containing 5cm of barely simmering water, without the bowl touching the water - it will take 5-10 minutes to become melted, smooth and glossy. Stir, then take off the heat and leave the mixture to cool for 5 minutes or so, until it feels just warm.
Now, in a separate bowl, beat the cream to the floppy stage. Fold half into the chocolate mixture and then fold that mixture into the rest of the cream. When it is smoothly blended, spoon it into the prepared tin. Tap the tin gently to even the mixture out, cover with clingfilm and chill overnight.
Just before serving, run a palette knife round the edge to loosen the torte, then give it a good shake and turn the whole thing out on to a serving plate (don' t be nervous about this - it's very well behaved). To serve, dust the surface with sifted cocoa powder and a few amaretti biscuits and, if you like, mark the top into serving sections. Have some chilled pouring cream to go with it; if you have any, a couple of tablespoons of amaretti liqueur will make a wonderful addition to the cream.
