In a shallow bowl or pie dish, whisk together the eggs, milk, vanilla extract, cinnamon, salt, and sugar until completely smooth and well combined.
Heat a large skillet or griddle over medium heat and add 1 tablespoon of butter, swirling to coat the surface evenly.
Dip one slice of bread into the custard mixture, letting it soak for 20-30 seconds per side. The bread should be saturated but not falling apart.
Lift the bread and let excess custard drip off, then place it in the hot skillet. Repeat with 2-3 more slices depending on pan size.
Cook for 3-4 minutes on the first side until deep golden brown and crispy. Flip and cook another 3-4 minutes on the second side.
Transfer cooked slices to a serving plate or keep warm in a 200°F oven while you cook the remaining batches, adding more butter to the pan as needed.
Serve immediately with maple syrup, fresh berries, powdered sugar, or your favorite toppings.
