Bread or cracker crumbs
Sunflower seeds
Sesame seeds
Chopped onions
Chopped chives, parsley, basil, oregano or other fresh herbs
Melted butter

Use any combination and amounts of the above that you desire depending on the size of casserole you are baking. Toss and brown lightly in melted butter in skillet. Add to top of casserole the last 10 to 15 minutes of baking.