Preheat the oven to 180 degrees C. Lightly butter 4 individual ramekins then divide the raspberries across the four ramekins.
Beat the egg yolks and caster sugar until pale and creamy. Transfer to a large bowl then combine in the ricotta, lemon zest and lemon juice.
In a separate bowl whisk the egg whites into stiff peaks then whisk in the sugar and vanilla.
Fold the egg whites into the egg yolk mixture. Spoon the mixture across the four ramekins. Place on a baking tray then bake in the preheated oven for 20 to 25 minutes or until puffed and lightly browned. Serve straight away.