I don't know how to make an authentic white sauce, but with this method you can make it in a frying pan very quickly. You can make a popular dish for children at home easily. You won't need to go to a restaurant anymore. Have a try.
Slice the onion thinly. Cut the bacon into small pieces. Spread the rice evenly on a gratin dish.
Heat some vegetable oil in a non-stick frying pan and sauté the onion until tender. Add the frozen seafood mix and continue to sauté. The frozen seafood mix doesn't have to be thawed completely at this point.
Add the milk, flour, butter, and soup stock cubes (break roughly beforehand). Stir well. Cover with a lid and cook over medium heat for 3 to 4 minutes until thickened.
The sauce should be thickened like this. Season with salt and pepper and pour the sauce over the rice in the gratin dish. Top with plenty of melting cheese and fresh panko (optional). Bake in an oven preheated to 200˚C for 5-10 minutes until golden brown on top.
Story Behind this Recipe
This is a recipe which was made originally for a 'Musui (no water) Pot'. I wanted to experiment with a similar recipe, using a normal non-stick frying pan with a lid instead of a Musui Pot. It was successful and tasty.
I used a non-stick frying pan with a lid. The sauce doesn't become lumpy or burn on the bottom of the pan. All you have to do is add all the ingredients, stir together and cover with a lid. After Step 3, you can pour the sauce over pasta to make seafood pasta. Pour into a gratin dish without the rice and bake to make seafood au gratin. The key ingredients are onion, bacon, and soup stock cubes. Apart from them, you can add any ingredients you like. The sauce goes well over toast too.