Preheat the oven to 350º F and gather a large baking sheet. Add cubed bread to baking sheet and bake for 8-10 minutes, tossing half way through, until bread is lightly toasted. Remove from oven.
Grease a 8x8-inch baking dish. Add the toasted bread cubes to the baking dish and set aside.
In a medium bowl, combine almond milk, eggs, pure maple syrup, vanilla extract, cinnamon, and salt. Whisk until combined, then pour the mixture over the cubed gluten-free bread.
Lightly press down on the bread with a spatula to make sure all of the bread is covered in the egg mixture. Cover the baking dish and refrigerate for at least an hour or overnight.
Remove the baking dish from the refrigerator to allow it to come to room temperature, then preheat the oven to 350º F. Press down on the bread, using a spatula, to help the bread soak up the egg mixture.
Top mixture with ¾ cups of the fresh berries, leaving ¼ cup for serving, then bake the french toast casserole for 45-50 minutes, until the egg custard is set and the top is a light golden brown. If the casserole starts to brown too quickly, cover it with aluminum foil while baking.
Let casserole cool for 5-10 minutes before slicing. Top with remaining ¼ cup of fresh berries and a dusting of confectioners' sugar. Drizzle each serving with additional maple syrup (optional).
Notes
This easy gluten-free French toast casserole is fluffy and light on the inside and has a crunchy top.If you're in a hurry, you could skip toasting the bread cubes; however, toasting makes for a better French toast casserole, so I highly recommend it. Toasting the bread helps the bread soak up the egg mixture better. If your bread is slightly stale and dried out already, you can skip this step.You can skip the berries if you wish to have a cinnamon raisin French toast casserole. The berries will add color and texture, so I prefer to use them.It is best to soak the bread cubes for at least an hour, but you can even leave them to soak overnight if you want to make this breakfast dish the night before and bake it in the AM. Soaking the bread longer will give you a moister French toast casserole as a result. If you don't have cinnamon raisin bread, add 1/4 cup of raisin and 1 tsp of cinnamon to the mixture before baking (optional).