How do you soften butter in a jar?

To soften butter in a jar (or using a jar), you can use a simple heat-transfer method: heat the jar, then use it to gently warm the butter stick.

Here's the method based on the provided YouTube reference:

1. Heat water in a microwave-safe jar (or glass).
2. Pour the hot water out of the jar.
3. Immediately place the heated jar upside down directly over the stick of butter on a plate.
4. Let it sit for approximately five minutes.
5. Remove the jar, and the butter should be softened.