Pour melted butter into a 13 x 9-inch glass baking pan. Tilt pan to coat bottom evenly. Arrange bread slices in a single layer in pan.
Whisk eggs in a medium bowl until well beaten. Add 2/3 c orange juice, 1/4 c sugar, and nutmeg. Pour over bread and cover with plastic wrap. Refrigerate overnight.
Preheat oven to 350 degrees F.
Remove plastic wrap from pan and bake, uncovered, 20 minutes. Sprinkle pecans and cinnamon over top and bake 10 minutes longer.
To prepare syrup: melt 1/4 c butter in a small saucepan over medium heat. Add 1/2 c orange juice and 1/4 c sugar. Cook thoroughly until heated and sugar has dissolved. Do not boil. Serve with French toast.