Fish Baked in White Sauce (Bechamel)- The Failproof Sauce!

This is a recipe that, frankly, has been around in my family for so many years and has been cooked so many times, and by so many different people, that I don't know who to attribute it to. It is a very quick-to-do dish, which I think is a fusion of Kerala and French cuisine, since the town of Mahe, where my dad is from, was a French colony that geographically lies in Kerala.
I don't know if I can safely take the credit for turning this dish into a bake. The one version of it that I remember, even after 15 years, was made by Chandrammayi, my father's aunt, in Pondicherry. If it had to stick in my mind this long, you can imagine how yummy it was…anyway, here's the recipe without further ado!
The short story (for the seasoned cooks):
Shallow fry fish slices after marinating in some masala (given below). Make the white sauce. Plonk the fish slices in the white sauce and serve (this is the original). My version is to transfer this to a baking dish and bake for 10-20 minutes. Both versions are delicious. Your call!

The long story:
Serves 4. Serve with plain bread slices or even better, garlic bread :-)
• Fish slices (the fleshy variety, preferably sear fish)    4 big or 8 small, thinly cut slices
For the marinade:
1. Turmeric             1 teaspoon
2. Chilli powder       1 tablespoon
3. Salt                    To taste
• Make a paste of these with a little water and smear onto the fish slices. Let it rest for 10 minutes and then shallow fry it for just 2-3 minutes on each side, very lightly. Keep aside.
For the white sauce:
(Make sure the whole process is done on low heat)
1. Butter                    1 tablespoon
2. Milk                      1 cup (add more depending on consistency needed)
3. Plain flour (maida)  1 tablespoon
4. Salt and pepper to taste
• Add the flour and mix it well, making sure it doesn't brown.
• Slowly stir in the milk and mix well, making sure that no lumps are formed. If needed, take the pan off the flame during this stage. Do not let it become too thick if you plan on baking this.
• Season with salt and pepper.
• To Garnish:
1. Tomato             1 big, sliced in thin circles
2. Cheese             Grated, enough to cover the dish
3. Bread crumbs    3/4th cup

• Arrange the fish slices on a bake-n-serve dish, pour the white sauce over the slices, arrange thin tomato slices on top, and grate any soft cheese over it. Sprinkle a thin layer of bread crumbs on top.
• Bake in a 180 C preheated oven for 15-20 minutes, or until the top becomes golden brown.
TIP: For this dish, I make the bechamel in the same pan in which the fish was fried. That way, the sauce takes on a little bit of the character of the marinade and becomes all the more yummy.
Also, you can bake just about anything with white sauce-mushrooms, vegetables, chicken, pasta (never tried it with lamb, though). You could season the sauce with dried or fresh herbs. You could add grated cheese or cream in the end,  making it a cheese sauce that goes well with pasta/macaroni.
Whatever you do, you could never go wrong with a white sauce!