Preheat oven to 325° Fahrenheit.
Place large cast-iron skillet on stovetop over medium heat. When skillet is warm, add ¼ cup ghee. Let ghee melt completely, swirling and tilting skillet as needed to distribute ghee across entire surface.
When ghee has melted, add 2 medium sweet potatoes, peeled and diced, to skillet. Stir to incorporate.
Sauté sweet potatoes, stirring often, 5 to 10 minutes or until sweet potatoes begin to soften.
When sweet potatoes have just started to soften, add 2 medium apples (cored and diced), 1 ½ teaspoons ground cinnamon, 1 ½ teaspoons pumpkin pie spice, and 1 cup organic unsweetened raisins. Stir to incorporate.
Sauté mixture, stirring often, 8 to 10 minutes or until raisins are plump and apples and sweet potatoes can be easily pierced with fork. Note: if needed, stir in small amounts water to prevent sticking and burning.
When apples, sweet potatoes, and raisins are ready, add ⅓ cup roughly chopped walnuts and ¼ teaspoon salt. Stir all ingredients to combine, then continue sautéeing mixture 2 to 3 minutes.
While mixture sautées, crack 8 large eggs directly into medium mixing bowl. Add 1 cup 100% pure pumpkin purée, vanilla bean seeds (optional), and ½ cup unsweetened, full-fat coconut milk. Stir until ingredients are fully combined.
Remove cast-iron skillet from heat and let cool slightly, then pour egg mixture into skillet. Use silicone spatula or back of spoon to smooth out ingredients, spreading mixture evenly across skillet.
Place cast-iron skillet in preheated oven. Bake dish 20 minutes, or until eggs are fully set. To check doneness, insert butter knife in center of pumpkin bake, then remove knife and check. When knife comes out of pumpkin bake cleanly, remove cast-iron skillet from oven and set aside.
Let dish rest 5 minutes, then slice pumpkin bake into desired number of servings. Serve warm.