Do the following things:

1. heat oil, once heated add butter

2. add onions on low heat until they are caramalized (not browned)

3. add the crushed tomatoes

4. lay the marinated diced chicken over the tomatoes and leave for 5 minutes - do not stir too much

5. add 0.5 cup hot water, and add salt to taste

6. simmer the chicken for about 30 minutes

7. add cream

8. add water to taste

9. leave on stove until it just boils