My birthday dinner with the fam featured poppyseed chicken - catered, not homemade - but I do have a recipe for something similar. You could lighten this by using reduced-fat, low-sodium soup, fat-free sour cream and reduced-fat crackers. Can't get around the stick of butter, though.
4 chicken breasts, cooked and diced
1 can cream of chicken soup
1 (8-oz.) carton sour cream
1½ T fresh lemon juice
1 sleeve Ritz crackers
2 T poppy seed
1 stick butter, melted
Distribute chicken evenly in bottom of 8-x-11-inch baking dish. Stir together (undiluted) soup, sour cream and lemon juice. Pour soup mixture over chicken. Crush crackers and mix with poppy seed. Sprinkle on top of soup mixture. Drizzle with butter. Bake uncovered at 350 degrees for 25-30 minutes.