Fat-free cream cheese, IMHO, wouldn't be a great substitute for ricotta
anyway - wrong texture. What I use is either .5% fat Quark cheese, which I
(in my smallish Ontario town) can find at any grocery store, or the dry
cottage cheese. Dry - but NOT pressed - cottage cheese is actually the
best. Tastes like ricotta, looks like ricotta... The pressed kind will work
too, but it's really BONE dry, and needs a bit of reconstitution with a
touch of skim milk and a hand mixer (so as not to completely puree it)
before it has the proper consistency.
If you can find a skim goat cheese, that would make a great flavour
compensation for the loss of the feta. Or maybe some lemon juice in the
spinach...
Yours,
Katharine