Step 1: In a large, shallow dish or bowl, whisk together the eggs, pumpkin puree, milk, brown sugar, vanilla extract, pumpkin pie spice, optional cinnamon, and salt until smooth and well combined. Ensure there are no lumps of pumpkin puree.
Step 2: Dip each slice of bread into the pumpkin custard, allowing it to soak for about 30 seconds to 1 minute per side, or until thoroughly saturated but not soggy. Thicker bread may require a slightly longer soak.
Step 3: Heat a large non-stick skillet or griddle over medium heat. Add 1 tablespoon of butter or oil. Once melted and shimmering, carefully place 2-3 soaked bread slices into the pan, ensuring not to overcrowd.
Step 4: Cook for 3-4 minutes per side, or until golden brown and cooked through. The French toast should be beautifully caramelized on the outside and custardy on the inside. Add more butter or oil as needed for subsequent batches.
Step 5: Transfer the cooked pumpkin French toast to a plate. If serving immediately, dust with powdered sugar, drizzle with warm maple syrup, and add any desired toppings like whipped cream or toasted pecans. For a crowd, you can keep finished slices warm in an oven preheated to 200°F (95°C) while you finish cooking the remaining batches.
Step 6: Serve warm and enjoy your cozy fall breakfast!