Place 300 gram strawberries and 6 tablespoons sugar in a food processor and process until smooth (about 30 seconds – 1 minute).
Add cream cheese, vanilla essence and lemon zest. Pulse 2-3 times till just blended. In case you don’t have a food processer, this step can be done in a blender or chopper.
Take out 3 tablespoons cream in a microwave safe bowl. Sprinkle gelatin and whisk to mix. Let stand for 5 minutes to dissolve. Heat the gelatin in 5-10 seconds interval in the microwave until just melted. Be careful when heating. Stir the gelatin mixture into the strawberry mixture.
Using an electric beater, beat the heavy cream with 2 tablespoons icing sugar in a large bowl until soft peaks start to form.
Add strawberry mixture and whisk on low speed until just blended. Be careful not to over-beat as it can split.
Spoon the mousse into a large serving dish or individual sized ramekins. Top with the remaining sliced strawberries and grated chocolate.
Cover with plastic wrap and place in the fridge for at least 2 hours to set and chill before serving.