The compare-cooking.perl script is meant to help viewing the differences
between periodical "What's cooking" messages, and can be used as an
external diff driver by:

    $ git config diff.whatscooking.command ./compare-cooking.perl

to produce this section in your .git/config

    [diff "whatscooking"]
	command = ./compare-cooking.perl

You can use e.g.

    $ git log -p --ext-diff whats-cooking.txt
    $ git show --ext-diff whats-cooking.txt

to review the history.