Melt chocolate either in a microwave or in a bain marie or a double boiler. Whisk it well. Give a small cut on one side of the rim of the plastic cups. Pour the melted chocolate inside the cups and swirl them so that the chocolate coats the cups entirely.
Pour out excess. Keep the cups in the refrigerator to set. Whip cream with powdered sugar till it stands in peaks. Quarter one strawberry and set aside.
Chop the rest and place them in a bowl. Add most of the whipped cream and mix.
Take the cups out of the refrigerator and peal the plastic away from the chocolate starting from the small cut given on the rim. Fill up the chocolate cups with the strawberry cream.
Top with some of the remaining whipped cream. Place a slice of strawberry on top and serve immediately.