1. Preheat your oven to 425°F. Scrub and peel your sweet potatoes if you want, wrap in aluminum foil and roast until tender, 60-75 minutes.
2. Wrap your peeled banana in aluminum foil and pop it in for the last 25 minutes.
3. Let cool and then smash them together. Add your walnuts, butter, brown sugar, cinnamon and salt and pepper.