RewriteEngine On

RewriteCond %{HTTP_HOST} prosperositygroup\.com$ [NC]
RewriteRule ^ https://www.prosperositygroup.com [R=301,L]

RewriteCond %{HTTPS} off [OR]
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^ https://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]