You'll describe your new job as a gravy train if it's almost effortlessly easy and pays really well.
Any source of income that requires very little effort on your part can be called a gravy train, whether it's a cushy job or a shady moneymaking scheme. The phrase is American in origin, although it's equally popular today in Britain. In the United States in the 1920's, gravy train was a common slang expression among railroad workers, meaning "an easy, short haul that pays well."