Preheat your oven to 400°F (200°C). Peel and cube the sweet potatoes, then toss them in a large bowl with extra virgin olive oil, ground cinnamon, and nutmeg. Spread the coated sweet potatoes evenly on a baking sheet. Roast for 50-60 minutes, stirring halfway through, until they are tender and edges are golden brown.

Once roasted, transfer the sweet potatoes to a mixing bowl. Add almond milk, vanilla extract, brown sugar, pure maple syrup, ground cinnamon, nutmeg, optional allspice, organic raisins, and marshmallows. Using a potato masher or fork, mix until well combined for a creamy texture; be sure to leave some small chunks for added interest.

Grease a 9x13-inch baking dish with butter or olive oil to prevent sticking. Pour the sweet potato mixture into the dish, spreading it out evenly. Tuck small pieces of unsalted butter throughout the filling for richness, and sprinkle additional marshmallows on top if you want extra sweetness before proceeding.

In a small bowl, combine raw pecans with a drizzle of maple syrup, mixing until the pecans are well-coated. Evenly pour this mixture over the top of the casserole to create a crunchy topping.

Cover the casserole dish with aluminum foil and place it in the preheated oven at 375°F (190°C). Bake for 15 minutes before removing the foil; continue baking for an additional 15 minutes until the topping is golden brown and the edges are bubbly.