Here is one i created to do the same. Just pass it the name of your site (It assumes that your pool is the same name as the site. )
### Get the parameters from the command line
#
param([string]$sitename)
### Import all the modules we need
#
Import-module WebAdministration | out-null
### Restart the site
#
Restart-WebItem iis:\sites\$sitename
Restart-WebItem iis:\apppools\$sitename