How do I clean burnt on food. On my Pyrex pans? Thanks?

Pyrex is glass. Same principle as paint on glass. :D

On my clear Pyrex I use a single edge razor blade or a paint scraper on the flat parts and a nut pick in the cracks. Always test first on any pan with decoration. You don't want to scrape off the paint.

This also works on glass top stoves and Corning ware BTW. Don't forget to test first just in case.

I would try Cerama Bryte, the glass cook top cleaner. Assuming you've washed them first.

And brillo pads. I keep one in the freezer between usage to stop it from rusting

Soak in very hot water and granular electric dishwasher soap. Should easily clean up after overnight soak.

Soak in hot water with baking soda. Let it sit for a while and then use a scrubber to remove. Cerama Bryte, used for stove top glass also works well.