Preheat the oven to 375°F and grease a 9x13” baking dish with vegan butter or coconut oil
Set a large pot of water to boil and add the cubed potatoes. Cook until fork-tender, about 10 minutes. Drain and transfer cooked potatoes to a large mixing bowl.
To the mixing bowl, add the coconut milk, maple syrup, coconut oil, vanilla extract, cinnamon, nutmeg, and salt. Mash the potato mixture with a potato masher or large fork until it reaches your desired consistency.
Transfer the mashed sweet potato mixture to your prepared baking dish and spread it into an even layer
In a medium-sized bowl, combine the crumble topping ingredients. Mix well to combine, then sprinkle this over your sweet potato mixture.
Bake the casserole for 25-30 minutes until the top is golden brown and crisp
Allow the casserole to cool for 5 minutes before serving