Heat oil in a large skillet over medium-low heat.
Add the onion and cook, stirring occaisonally, for 7 minutes.
Sprinkle with the curry powder and cook and additional 1 minute.
Add the yogurt and cream; simmer for 3 minutes.
Stir in the salt, pepper and tomatoes (if using).
Remove from heat and stir in chicken.
Scoop rice into bowls and pour hot chicken mixture over the top.
Sprinkle with peanuts (if using) and serve!