Preheat oven to 350°F and grease a twelve-hole muffin tin.
In a large bowl, whisk together the eggs, half and half, brown sugar, cinnamon and vanilla.
Add the bread cubes and the berries, if using, and stir until well-coated.
Scoop into prepared muffin tin, filling almost all the way to the top of each.
In a small bowl, combine the crumb topping ingredients and spoon over the muffin cups.
Bake for 18-20 minutes or until the tops are a light golden brown.
Sprinkle with powdered sugar, if desired, and serve with warm maple syrup.