Bring a pot of salted water to a boil. Add the sweet potatoes and cook until very soft, about 20 minutes. Drain the potatoes, then cover and keep warm.
Meanwhile, melt 2 tablespoons of the butter in a large skillet over medium heat. Add the allspice, vanilla bean, cinnamon and star anise. Toast the spices, stirring occasionally, until fragrant, about 3 minutes. Add the orange quarters and banana slices, raise the heat to medium high and cook, flipping the fruit once, until slightly brown, about 2 minutes per side. Add the maple syrup to the skillet, cover, remove from the heat and set aside to allow the flavors to meld for about 30 minutes.
Squeeze the juice from the orange quarters into the syrup mixture and discard the peels. Remove and discard the spices, being careful not to lose any of the syrup.
Puree the warm sweet potatoes in a food processor, slowly adding the cream and remaining 6 tablespoons butter. Add the banana-syrup mixture and puree until fully incorporated. Season to taste with salt and pepper and serve warm.