Preheat the oven to 180 degrees C. Spread oats out in a thin layer on a baking tray. Toast in the preheated oven for about 10 minutes, or until nut-brown. Set aside to cool. Remove them from the tray for faster cooling.
In a medium bowl, whip the cream to firm peaks, but not grainy. Gently fold in the icing sugar, vanilla and toasted oats. Spoon into 4 serving bowls and top with fresh berries. Drizzle a bit of dark rum over each serving. Garnish with a mint leaf.