Just do what @9peppe said and add below in your server block for port 443.
if ($host = www.outsidetheasylum.blog) {
return 301 https://outsidetheasylum.blog$request_uri;
}
You can continue to use the Certbot --nginx
plugin as you have been. It will create a temp response in your port 80 server block for the challenge and the above "if" statement in your port 443 server block is not involved in the cert challenge.