Place onions, curry powder, garlic, ginger, lemon juice and yoghurt into a blender or food processor and mix to puree.
Place puree and chicken into a pan and slowly bring to boil. Simmer gently until chicken is cooked, then remove chicken and place in a 2 litre casserole. Reduce sauce to 1 cup, add to chicken.
Boil rice for 5 minutes, drain well and place on top of chicken. Add bay leaf, sprinkle with milk and seal casserole well, using a sheet of foil if necessary.
Bake at 180c for 45 - 60 minutes until rice is tender.
Serve with vegetable curry, fruit chutney and pappadams.