Preheat your oven to 350°F.
Grease a 9x13-inch baking dish with butter or a dairy-free alternative.
Arrange the loosely chopped cubed bread in the greased baking dish. You can overlap them slightly to fit if needed.
In a large mixing bowl, whisk together the eggs, milk, maple syrup, vanilla extract, ground cinnamon, ground nutmeg, and salt.
Pour the egg mixture evenly over the bread slices, making sure all the bread is soaked. You may gently press down on the bread slices to help them absorb the mixture.
Let the mixture sit for about 15-20 minutes to allow the bread to absorb the liquid.
Place the baking dish in the preheated oven and bake for 25-30 minutes, or until the French toast is puffed, golden brown, and set in the center.
Remove the gluten-free baked French toast from the oven and let it cool for a few minutes before serving.