Preheat oven to 350 degrees F. Lightly grease a 3-quart rectangular baking dish; set aside. In a medium saucepan combine brown sugar, butter, amaretto, and corn syrup. Cook and stir until mixture comes to boiling. Boil, uncovered, for 1 minute. Pour into the prepared baking dish. Arrange bread slices over brown sugar mixture.
In a medium bowl combine eggs, half-and-half, vanilla, salt, and nutmeg. Pour evenly over bread slices. Press lightly with a rubber spatula or the back of a large spoon to moisten all of the bread. Cover and chill for 4 to 24 hours.
Preheat oven to 350 degrees F. Bake, uncovered, for 40 to 45 minutes or until a knife inserted near the center comes out clean and the top is lightly browned. Let stand for 15 minutes before serving.
Meanwhile, if desired, in a small bowl combine blackberries and granulated sugar; lightly crush berries. Let stand until a syrup forms, stirring occasionally. Spoon berry mixture over each serving.