Does MySQL included with MAMP not include a config file?

Some standard my.cnf variants can be found at /Applications/MAMP/Library/support-files/

Invoking mysqld --verbose --help | less on the MAMP mysqld binary reports:

Default options are read from the following files in the given order: /etc/my.cnf /etc/mysql/my.cnf /Applications/MAMP/conf/my.cnf ~/.my.cnf

Copy one of the variants in /Applications/MAMP/Library/support-files/ to one of the locations in mysqld's search order above, and you should be good to go after restarting the daemon.

The MySQL server of MAMP (not PRO) will be started without any my.cnf file. But you can create your own my.cnf file.

1. Stop servers
2. Create a my.cnf file in /Applications/MAMP/conf/
3. Add your content in to my.cnf
4. Save my.cnf
5. Start servers

You do not have to put a complete configuration in the my.cnf file. You can just add parts of a configuration ... for example:

[mysqld]
max_allowed_packet = 64M