Speaking of which...

Meaning

Transitioning to a related topic.

Examples

• John: I just saw a documentary on climate change.
• Alice: That's important. <b>Speaking of which</b>, did you hear about the new environmental initiative?
• John: No, I didn't. Tell me more.
• Alice: It's aimed at reducing carbon emissions. <b>Speaking of which</b>, we should carpool to work more often.