function Create-BasicAuthHeader {
  Param(
    [Parameter(Mandatory=$true)]
    [string]$Name,
    [Parameter(Mandatory=$true)]
    [string]$PAT
)

  $Auth = '{0}:{1}' -f $Name, $PAT
  $Auth = [System.Text.Encoding]::UTF8.GetBytes($Auth)
  $Auth = [System.Convert]::ToBase64String($Auth)
  $Header = @{Authorization=("Basic {0}" -f $Auth)}
  $Header
}

Invoke-WebRequest -Uri 'https://dev.azure.com/<organisation name>/_apis/projects' -Headers (Create-BasicAuthHeader 'Azure TOKEN_NAME' '<personal access token>') -Method Get