Grease a 9"x13" casserole with vegetable oil or butter. Cut up French bread into cubes and add to casserole (fill up to ~3/4).
In a large bowl, combine eggs, milk, vanilla extract, cinnamon, and brown sugar. Whisk mixture and mix well. Pour mixture into casserole.
Slice strawberries. Top casserole with strawberries and blueberries.
Wrap the casserole with saran wrap and refrigerate for four hours, or up to overnight.
Pre-heat oven to 350 degrees F. Bake for 35-50 minutes. Check at the 35-minute mark, and if it is not done bake for longer.
Sprinkle with powdered sugar.
Serve with maple syrup and enjoy!