Place the biscotti biscuits in a plastic bag and crush them lightly with the end of a rolling pin, leaving them slightly chunky. Tip the crushed biscuits into a bowl, drizzle over the Vin Santo and give it a stir. In small bowl, use a fork to slightly mash half of the strawberries with the sugar.
Whip the mascarpone in a medium bowl, then fold into the whipped cream. If the mixture appears too thick fold through a little milk. In a 1-litre glass bowl, spread half of the soaked biscotti. Top with half of the mashed strawberries and then half of the mascarpone mixture. Repeat until you have used up everything. Slice the remaining strawberries and scatter over the top. Refrigerate, then pack into a cooler as this dessert should be served chilled.