How would I hypothetically add a second capacitor boost stage to this circuit to brightly flash a white/blue LED?

Circuit is from the Talking Electronics website

 

Search "Joule Thief Circuit"
link
Home Made circuits
video

 

Search "Joule Thief Circuit"
link
Home Made circuits
video

Thank you! I've built a version of this using a joule thief arrangement, but I'd like to use a second capacitor stage for this one to understand it better