List Installed Jenkins Plugins with PowerShell

While looking to automate the installation of Jenkins I needed to get a list of installed plugins into a plugins.txt file to be used by the automated install process. It’s possible to view them in the GUI, but not get an easy export:

It’s possible to query the API to get this information:

Note: my test Jenkins server is not https, hence the need for the AllowUnencryptedAuthentication parameter