I love mushrooms, I wouldn't say they have that much of a steak like taste personally but they ado make a really "meaty" meal.
Garlic goes nicely with them, you could stuff with a mixture of cottage cheese, garlic, some herbs (fresh chives and parsley are nice) and perhaps a tiny sprinkle of a hard cheese like parmesan or gran padano.
I have seen people stuff them with a massive variety of things, from meditteranean vegetables to spinach and feta cheese. (though obviously feta can be high fat but you'd only need a little)
Hope that helps a bit - sorry I don't seem to have a lot of recipes I quite like them just as they are