Preheat the oven to 375°F (190°C). Grease a 9x13-inch baking dish lightly with cooking spray or butter.
In a mixing bowl, whisk together the eggs, milk, vanilla extract, ground cinnamon, nutmeg (if using), and granulated sugar until well combined.
Lay the slices of bread in the greased baking dish in a single layer. If needed, cut the bread to fit.
Pour the egg mixture evenly over the bread, ensuring each slice is soaked. Cover with plastic wrap or aluminum foil and refrigerate for at least 30 minutes or overnight for the best results.
In another bowl, combine the breadcrumbs and melted butter. Mix until the crumbs are well coated.
Remove the bread from the refrigerator and sprinkle the breadcrumb mixture evenly over the soaked bread slices.
Bake in the preheated oven for 25-30 minutes, or until the top is golden brown and crispy.
Once done, remove from the oven and allow to cool for a few minutes. Cut into individual pieces and serve warm, dusted with powdered sugar and drizzled with maple syrup if desired.
For added flavor, consider including fruits like blueberries or strawberries between the bread slices before adding the egg mixture.
Adjust the sweetness according to your preference by adding more or less sugar.
Store leftover baked French toast in the refrigerator and reheat in the microwave or toaster oven.