Place the quartered strawberries in a microwaveable bowl and microwave for 3 minutes on high. Roughly mash with a fork and set aside to cool completely.
Place the marshmallows and white chocolate in a saucepan with 1 tablespoon water and melt over a low heat. Leave to cool for 1 minute.
In a separate bowl, whisk the double cream with the vanilla extract to a soft peak.
Fold the cream into the marshmallow mixture, then add the cooled strawberries, stirring gently to give a swirl effect.
Spoon into glass dishes or coffee cups and top with the strawberry slices and chocolate curls. Chill in the refrigerator for at least 2 hours before serving.