Add-Type -TypeDefinition @'
    public class BaseMembersTestClass
    {
        protected internal virtual int TestMethod()
        {
            return 1001;
        }
    }
'@
$derived = Invoke-Expression @'
    class BaseCallTestClass : BaseMembersTestClass
    {
        [int] TestMethod()
        {
            return 3 * ([BaseMembersTestClass]$this).TestMethod()
        }
    }

    [BaseCallTestClass]::new()
'@

$derived.TestMethod()

> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      6.0.3
PSEdition                      Core
GitCommitId                    v6.0.3
OS                             Microsoft Windows 10.0.17134
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0