In a shallow dish, whisk together eggs, milk, cinnamon, sugar, and vanilla extract until well combined.
Heat a well-seasoned cast iron skillet or stainless steel pan over medium heat and add a small amount of cooking oil, ensuring the surface is evenly coated. See Note #1 below.
Dip each slice of bread into the egg mixture, ensuring they're evenly coated but not excessively soaked. Aim for about 15-20 seconds per side to achieve the desired consistency.
Place slices of the coated bread onto the preheated skillet or pan, allowing them to cook until golden brown and crispy on one side, about 2-3 minutes.
Flip the slices and cook the other side until golden brown and crispy as well, adjusting the heat if necessary to prevent burning.
Once cooked to your desired level of crispiness, remove the French toast from the pan and serve immediately with your favorite toppings such as butter, maple syrup, fresh berries, or powdered sugar. See Note #2 below for additional toppings.
Repeat with the remaining slices of bread.