The vanilla custard must be warm but not boiling so the gelatine can dissolve. Next, it has to be at room temperature before you can fold in the whipped cream or otherwise it will collapse.
Ideally, make the fraisier the day before so it has the time to set and firm up overnight. Serve at room temperature.
This version is less heavy than the traditional French ‘fraisier’.
Garnish the fraisier with chopped pistachio nuts.