KLM has quite standard (unfortunately very often high-calorie) arrangements on the tablets in C class:
1.) One plate with cheese and meat and maybe a very small salad (salad mostly on flights during lunch or dinner time // in general, potato salad or noodle salad)
2.) One plate with a desert (cake)

You get (warm) rolls and of course tea/coffee/OJ/water/.... I was only on flights with a flight time between 1:00h and 1:30h. All meals were cold. I don't know if the (somewhat) longer flight to FCO has a warm meal.

I can't compare with breakfast service on Northwest. IMO, KL C-class is quite ok (FAs take/bring your jacket; pre-boarding for families with children/people needing help, then C-class). Don't expect white linen or hot towels (towels in plastic only).