I think it's going to be a case of
that one looks good, now what are the fats and what are my choices: reduce amounts? Change to unsaturated -- hey did Rachel Ray put EVOO in any of these?
Tuna casserole has got to be one of the more forgiving recipes known to humanity.
Where I'd start with this is rather twofold: whole wheat or other wholegrain pasta only to enhance the fiber, and halve the fat content. How lowfat is low fat, btw? What do you need to do? Keep an eye out for reduced fat cream of mushroom soup; I daresay somebody's making the stuff now. The Martha Stewart method takes more woman-hours: scratchbuild your own reduced cream of shroom.
{Now it's time for me to go untimely stimulating my appetite looking for cream of shroom recipes... off I go.}
She did!! It's not quite a casserole, but it could be done up as one, and is doubtless good either with its original chicken, or with tuna substituted for the chicken.
Another, similar idea, also from Rachel's site. Chicken again, probably work with tuna, and an effort at reducing the fat content. We may be getting somewhere. "1/2 cup (2 handfuls) shredded Italian 3-cheese mix" I suppose is equal parts Parmesan, Romano, and Asiago. (But that is a SWAG -- Stupid Wild Ass Guess.)
I did search the site for her
Tuna Casserole Recipe. It's not at all low-fat. Got EVOO.