PowerShell add text line to multiple files

Question

Powershell experince 3 hours...

Scenario: need to add a line of code to the top of multiple ASPX files in multiple folders and subfolders

Is this possible?

I've figured out how to search for the files but adding that line of code is where I'm stuck. This is what I have, which is not working

Get-ChildItem C:\domain_3 -recurse -include "*.aspx" |
Foreach-Object { 
    Add-Content -Path $targetFile -Value "<%@ Page Language="C#" Inherits="LandingPages.LandingPage" %>"; 
}

Thank you all

Answer 1

$header=@"
"<%@ Page Language="C#" Inherits="LandingPages.LandingPage" %>
"@

Get-ChildItem C:\domain_3 -Recurse -Filter *.aspx | Foreach-Object { 
    $header`n" + (Get-Content $_.FullName | Out-String) | Set-Content -Path $_.FullName
}