Leave the ice cream out of the freezer for 5 mins to soften, then tip into a bowl. Meanwhile, put six of the biscotti into a freezer bag and lightly crush with a rolling pin, fold into the ice cream, then return to the freezer.
Break the chocolate into a pan or microwaveable bowl, add the brandy and heat gently until melted or microwave on High for 30 secs. Stir (it will thicken), then pour in the hot coffee and carry on stirring until smooth.
Scoop the ice cream into heatproof glasses or bowls, then pour the mocha over. Serve straight away with
the remaining biscotti.