Custom Facebook Identity Provider: Bread & Butter IO

Log in to the developer site of Facebook:

Click on My Apps at the top right, then click Create App.

Select Consumer for your app type, then click Next.

Enter your App's Display Name. We recommend using your company name for the App name, as this name will appear during the login process.
Click Create app.

Click Set Up for Facebook Login to add it as a product.

In the left menu, go to Facebook Login, then Settings.

For the Valid OAuth Redirect URIs, enter:

https://api.breadbutter.io/callback
Click Save Changes.

At the top of the page, click Get Advanced Access.

On the Permissions and Features page:

Repeat the same steps for the email permission.

In the left menu, go to Settings, then Basic.

Enter your Terms of Service, Privacy policy, and Data Deletion Instructions URLs.

Take note of the App ID and App Secret keys.

At the top of the page, toggle your app to Live.

Go to https://app.breadbutter.io/sign-in/
Click Sign In and authenticate (or Sign Up make a new account and authenticate).
Go to Settings in the left menu.
Click on Facebook under SSO Settings > Social Accounts.
Select "Set Facebook for Production".
Enter a custom name and description.
Enter the App ID from the Facebook setup steps above.
Enter the App Secret from the Facebook setup steps above.
Click Save.
Click the checkbox next to your new Facebook provider to enable it.