Please answer the following question by reasoning step-by-step.
Passage: I Ca n't Believe It's Not Butter! is a spread brand produced by Upfield.\n\nQuestion: Based on this passage, who makes i can't believe it's not butter?

Upfield
The important part for answering this question is: I Ca n't Believe It's Not Butter! is a spread brand produced by Upfield.

.

The answer: Upfield