I got the original recipe for this fish from a Jr. League cookbook back in the late 80's. I've adapted it a little to our taste. My kids love this and actually request it. I live on the coast and use fresh fish when I can but I also use the frozen tilapia sold in the grocery stores. I find it on sale a lot and it turns out just as good as fresh fish.
This recipe is based on using the frozen tilapia. If larger, thicker fillets are used; you may need to adjust seasonings and cook time.
Pre-heat oven to 350 degrees. Place the stick of butter in a 9x13 casserole dish and place in oven while it's pre-heating. This is the key to this dish. You want to brown the butter until it's almost burned but NOT burned. It takes a few minutes to start browning but once it starts - it happens quick. I usually swirl the dish around so the butter browns evenly. Once it's all brown, take it out and set on the counter. (leave a pot holder on the sides of the dish so you remember it's HOT)
Place the fish fillets in the browned butter. Sprinkle each fillet with the lemon juice, Worcestershire and then the Cajun seasoning. Place back in oven and let cook for about 5 minutes.
Pull dish from oven and carefully turn fillets over. Repeat with the seasonings and this time, add the Parmesan cheese. Place back in oven and let cook until the fish is white and flaky throughout.
When serving, after the fish is removed from the dish; pour the remaining butter into small containers and serve with the fish to dip it in.