Peel the sweet potatoes and chop them into 2-inch pieces. Place the sweet potato pieces in a medium saucepan and cover them with water. Bring the water to a boil and cook until the sweet potatoes are fork tender, about 30-35 minutes. Remove the saucepan from the heat and drain the water.
Preheat the oven to 350°F.
Place the boiled sweet potatoes into a high-speed blender or food processor. Add the eggs, butter, coconut milk, maple sugar, baking soda, cinnamon, and salt, and process the mixture until smooth.
Pour the mixture into a large soufflé dish and bake for 45-60 minutes. The soufflé will be done when you can gently shake the dish and the soufflé is firm but jiggles slightly.