Preheat oven to 350F.

Generously grease a 9×13-inch baking dish with salted butter.

In a large bowl, beat eggs, milk, sugar, vanilla and rum.

Add brioche cubes and let mixture soak for 5 minutes (best when refrigerate overnight).

Spoon into a baking dish.

Sprinkle with chocolate chips.

Bake for about 25-30 minutes, or until puffed and golden.

Cut into generous squares and serve with maple syrup over bread.