1Whisk eggs, milk, juice, vanilla, rum, sugar, cinnamon and salt in a bowl; set aside.
Place bread in a shallow baking dish in a single layer. Pour egg mixture over bread; soak 10 minutes. Turn slices over; soak 10 minutes.
Preheat oven to warm or the lowest setting. Place a wire rack on a baking sheet, and set aside. Heat 4 tablespoons butter in a skillet over medium-low heat. Fry half the bread slices until golden brown, 2 to 3 minutes per side. Transfer to wire rack; place in oven while cooking remaining bread. Wipe skillet, and repeat with remaining butter and bread. Keep in oven until ready to serve. Serve warm with additional butter and warm maple syrup.The rum is optional but tastes great.