Preheat your oven to 400°F (200°C). In a bowl, combine cubed sweet potatoes with olive oil, cinnamon, and nutmeg. Spread evenly on a baking sheet and roast for 50-60 minutes until tender and golden brown, stirring halfway through.

Lower oven temperature to 375°F (190°C) and grease a 9x13-inch baking dish. Mash the roasted sweet potatoes in a large bowl, mixing in almond milk, vanilla extract, butter, brown sugar, maple syrup, cinnamon, nutmeg, allspice, raisins, and half of the marshmallows.

Transfer the sweet potato mixture to the greased baking dish, spreading it evenly. Top with remaining marshmallows and small cubes of butter.

In a small bowl, mix raw pecans with maple syrup. Sprinkle this mixture over the sweet potato filling.

Cover with aluminum foil and bake for 15 minutes. Remove foil and bake for another 15 minutes until topping is golden brown and marshmallows are melted. Allow to cool slightly before serving.