Preheat the oven to 350 °F. Grease a muffin pan with cooking spray. Set aside. Slice sourdough bread into ½ inch cubes. Place in a large bowl and set aside.
In a medium mixing bowl, beat eggs well. Add milk, sugar, cinnamon, salt and vanilla. Mix well. Pour egg mixture over bread. Carefully mix to evenly coat all the bread cubes.
Let sit for ten minutes to soak in. In a small bowl, combine the flour, brown sugar and cinnamon for the topping. Cut in butter until you have small crumbles.