Steps
1. Preheat the oven to 350°F (180°C). Grease a baking dish with butter.
2. In a small bowl, soak the prunes in rum for 15-20 minutes.
3. In a mixing bowl, whisk together eggs and sugar until well combined.
4. Add milk, heavy cream, and vanilla extract to the egg mixture, and whisk until smooth.
5. Stir in the flour until just combined.
6. Place the soaked prunes in the bottom of the greased baking dish.
7. Pour the batter over the prunes.
8. Bake for 25-30 minutes, or until the clafoutis is set and golden.
9. Serve warm or at room temperature.