Coat 8×8-inch baking dish with nonstick spray. In large bowl, whisk together milk, eggs, sugar, vanilla, cinnamon, and nutmeg. Add bread slices and let stand 10 minutes to soak up some custard. Arrange slices in baking dish in two rows, standing up on end. Slowly pour any remaining custard over bread. Cover dish with plastic wrap and refrigerate at least 4 hours or overnight. Preheat oven to 350 degrees. Uncover dish and bake 45 minutes, or until bread puffs slightly and browns.