1. Heat the butter on a slow flame, add the onion and green chilli and fry for 1 minute.
2. Add the mushrooms and cook for 5 to 7 minutes.
3. Mix the cornflour with the milk and add to the mushroom mixture.
4. Add a little water if the mixture is too thick.
5. Add the oregano and salt.
6. Cook for a few minutes.

How to Proceed:

1. Brush a tray with oil and put the pizza crusts on it.
2. Spread some mushroom filling on each crust and sprinkle some cheese on top.
3. Bake in a hot oven at 200 degree C (400 degree F) for 10 minutes or until the cheese has melted.
4. Sprinkle chilli powder on top and serve hot.