Break up your white chocolate into pieces in a microwave safe bowl. Heat for 30 second increments, stirring after each blast until almost melted. Stir with a metal spoon to finish melting.
Add mascarpone and mix quickly with a spoon as if you were whipping cream to whip the white chocolate and mascarpone together to a mousse-like consistency that is smooth and velvety.
Top with fresh raspberries sprinkled over (discard any bad berries from the punnet as you go) and chill in the fridge until chilled and set. Most of the sugars in this recipe come from the raspberries so you can use less of them to lower the sugars and carb count.