The Better Butter Chicken

This is from Eat, Shrink and Be Merry.

The Better Butter Chicken
2 tbsp butter
1 c. chopped onion
2 tsp minced garlic
1 tbsp grated ginger
1 tsp chili powder
1/2 tsp ground tumeric
1/4 tsp cinnamon
1 can(19 oz) diced tomatoes, undrained
2 tbsp tomato paste
1 tbsp brown sugar
1/2 tsp salt
1/4 tsp ground pepper
1 whole cooked rotissierie chicken, skin removed, meat cut up(I used 6 chicken breasts)
1/3 c. light (5%) cream( I 1% milk)
1/4 c. light sour cream
1 tbsp minced fresh cilantro, I used more
Hot basmati rice ( I used sticky Japanese rice)

Melt butter in a deep, 10 " skillet over med. heat. Add onions and garlick. Cook slowly, stirring often, until onions are tender, about 5 min. Add gingerroot, chili powder, tumeric,and cinnamon. Cook 1 more minute. Add undrained tomatoes, paste, sugar, salt, and pepper. Reduce heat to low. Cover and simmer for 10 min. stirring occasionally.
Add chicken, cream, and sour cream. Simmer uncovered for 5 min. Remove from heat, stir in cilantro. Serve over rice.