This SharePoint Powershell script checks all of the web sites in a site collection and web application for a specific web template that is used.
$webApplicationName = "https://xxxx"
$cnt = 0
$path = "f:\temp\webTemplates.txt"
$wa = Get-SPWebApplication $webApplicationName
foreach($site in $wa.Sites)
{
$site.Url
foreach ($web in $site.AllWebs)
{
$web.Url
if($web.WebTemplate -like "HOMEPORTNWPROJ"){
$web.Url | out-file $path -append
}
}#end foreach web
}#end for each site