Cut chicken into small bite-sized pieces. Grease a casserole dish with butter.
Put butter in a frying pan over a medium heat. When butter has melted add chicken and onion and fry until onion turns translucent. Add mushrooms and fry together.
Remove from heat, add S&B Curry Powder and flour and mix well. Return to a low heat and stir-fry until powders are absorbed.
Add milk, salt and white pepper and continue to cook, stirring well, until milk thickens. Remove from heat.
Place white rice in gratin dish and cover with mixture. Sprinkle cheese over the top.
Cook in an oven toaster until the top browns, then sprinkle parsley to garnish.
