Place the shortbread biscuits inside a sealable plastic bag, then crush them using a rolling pin until they are reduced to small, uneven crumbs.
Distribute the crumb mixture evenly between two serving glasses, creating a base layer.
In a mixing bowl, combine the soft cheese with the finely grated zest of one lime and two tablespoons of icing sugar. Beat the ingredients together until the texture is smooth and creamy.
Spoon this mixture over the biscuit bases, using the back of a spoon to level the surface.
Allow the frozen mixed berries to thaw. Take half of the fruit and blend it with one tablespoon of icing sugar and the juice from the lime until a vibrant fruit purée forms.
Spoon this purée over the cream layer in each glass. Garnish with a handful of the remaining whole berries for a contrasting texture and appearance.
These individual cheesecakes can be enjoyed straight away, or placed in the refrigerator for several hours to chill and firm up before serving.
