Preheat the oven to 350 degrees Fahrenheit. In a large mixing bowl add all ingredients except the prunes and stir until well combined. To toast, add ingredients to a baking sheet and bake for 15 minutes. Stir occasionally to prevent burning. Add muesli back into the mixing bowl and stir in prunes. Enjoy with milk or on top of your favorite yogurt! This muesli is best when stored in an air-tight container and enjoyed within 2 weeks.