Oysters Mornay - cooking recipe

Ingredients

24 oysters (half shell, you can buy oysters in some parts of the world on the half shell, much easier, I can't I)
2 cups milk
1 cup grated gruyere cheese
2 tablespoons parmesan cheese
2 teaspoons cornflour
2 tablespoons parmesan cheese (extra)
rock salt

Preparation

Prep time is for oysters already halved.
Heat milk in a pan, when hot, mix a little water with cornflour, add to milk and stir until mixture thickens, it should be quite a thick consistency.
Add Gruyere and 2 tablespoons Parmesan stir until cheese has melted.
Pour rock salt into an oven proof dish enough to cover the bottom, helps oysters to sit evenly, place oysters in dish, spoon sauce over oysters to cover, sprinkle remaining Parmesan cheese over each oyster (note: 2 Tablespoons approx enough to cover.).
Grill Oysters until browned and bubbling.