Preheat oven to 350F. Melt butter in a large saucepan over medium heat. Stir in curry powder and saute apples, onions, and garlic until tender. Salt to taste. Stir in flour, add yogurt, cream, and stock gradually, mixing well after each. Cook until sauce is smooth and thick, stirring constantly. Add chicken.
Place cooked rice in the bottom of a shallow, buttered baking dish. Top with av ocado slices followed by chicken mixture. Bake 10 minutes, uncovered.