Preheat oven to 325º. Heat ghee in a large cast-iron skillet over medium heat, then add sweet potatoes. Cook, stirring often until beginning to soften, about 5-10 minutes.
Add in apples, cinnamon, pumpkin pie spice, and raisins, and cook until apples are softened and raisins are plumped, about 8-10 minutes. Both apples and sweet potatoes should be easily pierced with a fork. If necessary, add in a little water to prevent sticking and burning.
Add in in walnuts and salt, about 1/4-1/2 teaspoon to taste. Stir to combine well and sauté the mixture a minute or two.
In a medium bowl, whisk together the eggs, pumpkin purée, seeds from vanilla bean, and coconut milk until smooth and well combined. Remove apple-sweet potato mixture from heat and pour egg mixture over. Smooth to cover with the back of a spoon. Bake for 20 minutes or until set. A knife stuck in the middle should come out clean.