Any bread is lovely in this buttermilk batter.
Whisk together eggs, buttermilk, vanilla, cinnamon, nutmeg, and salt in a medium bowl; set aside.
Place bread in a shallow baking dish large enough to hold the bread slices in a single layer. Pour egg mixture over bread; soak 10 minutes. Turn slices over; soak 10 minutes more or until soaked through.
Preheat oven to 250 degrees. Place a wire rack on a baking sheet; set aside. Heat 1 tablespoon butter and 1 tablespoon vegetable oil in a large skillet over medium 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 out skillet; repeat with remaining butter, oil, and bread. Keep in oven until ready to serve. Serve warm with maple syrup, if desired.