If you are serving this for breakfast, prep the French toast the night before. If you are serving this for dinner, you can prep the French toast in the morning.
Slice the baguette into about 1/4" thick slices. Lightly butter or coconut oil an 8x8" glass baking pan. Lay the baguette slices in the pan. You should have two layers of the baguette slices.
In a small saucepan, melt the butter over medium heat. Remove it from the heat and stir in the maple sugar. Spread the butter and sugar mixture over the baguette slices.
In a small mug, combine the topping ingredients. Sprinkle it evenly over the French toast.
In a large mixing bowl, combine the egg, vanilla extract, cinnamon, nutmeg, and coconut milk. Beat until everything is combined. You can use a fork or hand beaters. Pour the egg mixture evenly over the baguette slices.
Cover the glass baking dish and put the French toast in the fridge. Let it set for 8-16 hours.
When you are ready to bake the French toast, preheat the oven to 375°F. Get the French toast out of the fridge to come to room temperature while the oven preheats.
Bake for 45-50 minutes. The center should not jiggle when you move the pan. Remove from the oven and let it set for 5 minutes. Cut, serve, and enjoy!