Preheat the oven to 350 degrees F. Butter an 8.5 inch by 4.5 inch nonstick bread pan.
In a small saucepan, heat the butter and maple syrup over low heat until the butter is melted. Stir occasionally.
In a large mixing bowl, whisk together the cassava flour, tapioca flour, salt, and baking powder. Add the melted butter mixture and give the mixture a few stirs, then add the eggs and the water. Stir until everything is combined.
Sprinkle the additional 1 tablespoon over the dough and use your hands to knead the dough into a bread loaf shape. You can sprinkle additional tapioca flour onto the dough if needed. Place the dough into the buttered bread pan.
Place the bread pan in the oven and bake for 30-35 minutes. The bread should sound hollow when you knock on it. Once the bread is done, remove it from the bread pan immediately and place it on a cooling rack.
Allow the bread to cool completely before slicing. You can cut the slices into your desired thickness. For french toast, thinner slices tend to work better since they soak up the egg mixture better.