There are some different versions on spark recipes: http://recipes.sparkpeople.com/recipes.asp
Check those out!
I would personally try to swap out greek yogurt for all (or at least half) of the sour cream, and/or use low fat sour cream instead.
I would use half ritz and half panko bread crumbs for the topping- and half the butter (or lite butter) instead!
I would also try to find a lower sodium/lower fat sub for at least one of those cans of chicken soup... or just make my own gravy/soup instead :)