Green’s Dictionary of Slang

(US) easy, undemanding of physical strength.

1915		Van Loan ‘Sporting Doctor’ in Taking the Count 23: Wade was indeed far gone when a cream-puff boxer like Mahoney could stand [...] with him.
1969		‘Iceberg Slim’ Pimp 65: It’s cream-puff work.
1990		D. Heilbroner Rough Justice 31: The officers who took me out explained that I was being given cream-puff treatment: no heavy radio runs to shootouts or raids, just a nice, safe patrol.