Brush butter on one side of French bread slices; place bread, buttered side up, on a baking sheet. Bake at 350° for 10 minutes until lightly toasted. Cut into 1/2-inch cubes; set aside.
Combine 1% milk and next 4 ingredients in a large bowl; stir well with a whisk. Add bread and raisins to mixture, pressing gently to moisten; let stand 15 minutes. Spoon bread mixture into a 13 x 9-inch baking dish coated with cooking spray. Bake at 350° for 35 minutes or until set. Serve warm with Rum-Raisin Caramel Sauce.