Broken cached html links :(

hello everyone,

I was playing around with some stuff while setting up the blog , and I have used a cache plugin ( dont’ remember exactly which one it was ) , and I ended up not using it . Afterwards , I changed my permalink structure.

so now I have broken cached html links that other sites are linked to already. I’m trying to find out what’s the best way to deal with this situation , assuming , by using 301 redirects.

Any suggestions would be appreciated.

To clarify :
old permalink structure :
https://iheartyum.com/2009/10/stuffed-acorn-squash/
old cached html link
https://iheartyum.com/2009/10/stuffed-acorn-squash.html
new link structure :
https://iheartyum.com/main-course/stuffed-acorn-squash/

I have a friend’s blog that’s linked to the html version…