Slice bread into ½" thick slices (8–10) and place on a wire rack over a baking sheet. Bake for 15 minutes (turn them over halfway through if you don’t use a rack). Let cool for 5 minutes.
Whisk eggs, milk, sugar, vanilla, cinnamon and salt in pie plate or medium-sized bowl until all the ingredients are well combined.
Heat a non-stick skillet or griddle over medium-low heat. Add 1 tsp each of butter and oil and heat until they shimmer. It’s better to cook slowly on medium-low heat and not rush it; this gives it enough time for the egg to cook all the way through and keeps the edges from burning.
Dip each slice of bread into the mixture, allowing it to soak completely through but not so much that it falls apart. Place wet slice onto skillet and repeat with the other slices as you soak them. Do not overcrowd the pan.
Cook for 2–3 minutes or until the toast is nicely browned. Flip slices over and repeat.
Remove toast from skillet. Place it back on the cooling rack and loosely tent with foil. Wipe skillet out with a paper towel, add the remaining butter and oil and repeat the process with remaining slices.
For less mess, dust toast with the powdered sugar over the drying rack. Plate the French toast and serve warm with butter and maple syrup!