Toast the oats in a dry frying pan over medium heat stirring so it doesn't burn. Remove from the heat and set aside to cool.
Beat the cream until stiff. Add the oats a handful at a time until desired consistency is reached. There shouldn't be too many oats; make sure it is still light and creamy.
Add caster sugar to taste, along with rum or vanilla.
Add some fresh berries and gently fold into the cream mixture. Serve straightaway.