Have you looked into the string interpolation & verbatim operators as a templating alternative? These can be combined to create complex, nested strings:

  var reportPartial = @$"
    <h1>{report.Name}</h1>
    <table>
      {string.Join('\n', report.Items.Select(reportItem => @$"
        <tr>
          <td>{reportItem.Col1}</td>
          <td>{reportItem.Col2}</td>
        </tr>
      "))}
    </table>
  ";

In more complex views or reuse scenarios, I'd push the inner interpolation loop to a method.

This is how I've been building my .NET web apps for the last ~3 years. @+$ = PHP in C# as far as I'm concerned.