A good ravioli filling:

{{{
1/2 cup grated Fontina, 6-8 chopped basil leaves,
6-8 baby portobello mushrooms (chopped and sauteed), 1/4 cup Parmesan
shavings. 
}}}
All amounts are relative, I didn't actually measure anything.
Mix it up, stuff some raviolis. Made some [http://www.pangloss.com/wiki/Recipe/FreshPasta pasta dough]. Stuffed 16 raviolis.
Boil 2-3 minutes. Served with pesto and top with more Parmesan shavings. Yummy and light.