For Better French Toast, Dry Bread Is Your Friend
Typically, the fresher your ingredients, the better. (We're not talking about things like cheese and wine, the quintessential "gets better with age" items). Bread, especially, is one food which isn't at its most appetizing when it's gotten stale. However, there's a particular dish that comes together better when made with bread that's a tad dry rather than a loaf that's fresh and springy: sweet, decadent French toast.
French toast depends on the bread soaking up the egg and milk mixture it's dipped in (also known as the custard) while still holding its shape and not becoming soggy or flimsy. Bread that is dry on the outside but still a little moist inside achieves this; it's just sturdier, tougher, and more up to the task. That's why French toast is called pain perdu ("lost bread") in French: By using stale bread that would otherwise have been "lost" to the dehydrating ravages of time, you give it new life and purpose, capitalizing on the unique strength that dryness brings.
If you don't happen to have any stale bread in your kitchen, you can still make French toast that's going to absorb your custard and hold up beautifully. All you have to do is dry out your bread first.
How to dry out bread to make French toast
The most hands-off way to zap the moisture from your bread is with a method you've possibly already used before, albeit by accident: leave your bag of bread open the day before preparing French toast. Exposed to the air all night, the bread should be workably stale by the time you're ready to whip up whatever twist on French toast you're in the mood for. If you don't want to dry up all your bread, you can always remove as much as you need and leave out only that amount. Still, there are oodles of ways to use stale bread, and this might be the time to experiment with them.
If your visions of gooey, buttery French toast need to manifest much sooner than air-drying can produce, there's a faster approach. Heating your bread in the oven at 285 degrees Fahrenheit should have it French toast-worthy in 15 minutes or so. Your toaster on a low setting works, too; just make sure you're not overdoing the heat. Remember: the goal is to keep the inside of the slices still moist. Bread that's over-toasted into major dryness won't soak up the custard effectively and can have an unpleasant texture.