Given the task definition and input, reply with output. In this task, you have to identify the named entities (NER) which are the ingredients required given its directions. Named entities are the names of the items without their quantity.

Chop onions, tomatoes and olives into small pieces., Grate cheese., Cover bottom of small casserole dish with 1/2 container of sour cream., Top with grated cheese, chopped onions, tomatoes and olives., Next, cover with other 1/2 container of sour cream. Again, top with grated cheese, chopped onions, tomatoes and olives., Refrigerate for 1 to 2 hours before serving.
tomato, onion, olives, sour cream, white Cheddar cheese