When the weather starts to get cooler, a warm, filling breakfast just makes more sense. You'll have to start this one day ahead of time, but it's well worth the wait.
Slice sweet bread into about 20 slices, 1" thick. Liberally spray a 9" x 13" baking dish with cooking spray and arrange bread slices in 2 rows overlapping the slices. In a large bowl, combine the eggs, half-and-half, milk, sugar, vanilla, cinnamon, nutmeg, and salt, and beat with a rotary beater or whisk until blended (but not too bubbly). Pour mixture over the bread slices, making sure they're evenly covered (get the mixture in between the slices with a spoon). Cover and refrigerate overnight.
The next morning, preheat oven to 350º F. Combine all the ingredients for the topping (melted butter, light brown sugar, macadamia nuts, coconut pancake syrup, ½ teaspoon ground cinnamon, and ½ teaspoon ground nutmeg) and spread evenly over the top of the bread. Bake for 40 minutes, until puffed and lightly golden. Serve with coconut pancake syrup.