In a large pot, heat the olive oil and butter until melted. Add the onion and garlic and sauté over medium heat until tender and translucent, about 6 minutes.
Add the cubed sweet potatoes and toss to coat with the oil, butter and onions. Pour in the chicken stock or water, sea salt and nutmeg. Bring to a boil and lower the heat to a simmer. Cook partially covered until the sweet potatoes are tender, about 20 minutes.
Add the maple syrup, coconut milk and cayenne. Cook until heated through. Puree soup with an immersion blender or in batches in a blender. Taste for seasoning. Serve immediately or allow to sit off the heat to thicken slightly.
Notes
*If you prefer to use more coconut milk, use a full can and use 1 cup less chicken stock.