Place sweet potatoes in a microwave-safe dish and cook in the microwave for 5 minutes. Add apples to the sweet potatoes and cook in the microwave until sweet potatoes and apples are tender, about 3 minutes more.
Arrange sweet potatoes in a 9x13-inch baking dish and slice each sweet potato down the middle. Place butter cubes into each sweet potato.
Mix rum, pecans, maple syrup, raisins, cranberries, stevia, and coconut oil together in a bowl. Stuff sweet potatoes with rum mixture and apples.
Bake in the preheated oven until filling is bubbling and fragrant, about 30 minutes.