If your bread is fresh, let the slices sit out on a wire rack for an hour or two to dry out slightly. This step is crucial because drier bread absorbs the custard mixture more effectively without becoming soggy, ensuring a better final texture.
In a shallow dish wide enough for a slice of bread, crack the eggs and whisk them until the yolks and whites are completely combined. Pour in the milk or cream and whisk again until the mixture is smooth and uniform.
Stir the grated cheese, chopped herbs, salt, pepper, garlic powder, and onion powder into the egg mixture. Whisk vigorously to ensure all the savory ingredients are evenly distributed, creating a flavorful custard for soaking the bread.
Place one slice of bread into the custard, letting it soak for about 20-30 seconds on each side. The bread should feel saturated but not be falling apart. Let any excess liquid drip off before moving to the pan.
Heat the butter or oil in a large skillet over medium heat. Once the butter is melted and foaming, carefully place the soaked bread slice in the pan. Cook for 3-5 minutes until the bottom is deep golden brown and crispy.
Flip the French toast and cook the second side for another 3-5 minutes. The center should feel firm to the touch but still have a custardy give. If the outside is browning too fast, reduce the heat to cook the inside through.