Pour melted butter into a 9 x 13-inch baking dish. Set aside.
½ cup butter, melted
In a small bowl, stir together brown sugar, cinnamon and nutmeg.
1 cup brown sugar, 2 teaspoons cinnamon, ¼ teaspoon nutmeg
In a separate bowl, whisk together vanilla extract, eggs and milk.
2 teaspoons vanilla extract, 7 eggs, 1 ½ cups whole milk
Arrange 6 bread slices in a single layer on the bottom of the buttered baking dish. You can cut the bread, as necessary, to fit the bottom of the dish.
12 slices frozen buttered Texas Toast (2 boxes), thawed
Sprinkle half of the sugar mixture over top.
Add another layer of bread slices. Pour egg mixture over the bread, and gently push down on the bread to make sure that they are evenly submerged.
Sprinkle remaining sugar mixture over top.
Cover with foil and refrigerate for at least 1 hour, or overnight. The longer it sits, the better!
When ready to bake: Preheat oven to 350F/180C.
Cover dish with foil and bake for 30 minutes. Uncover and bake for an additional 20 minutes, or until the casserole is set and the top is golden brown.
Drizzle with maple syrup or dust with powdered sugar just before serving.
Optional, for serving: maple syrup, powdered sugar, and/or fresh fruit