using System;

public class Program

{

    public static void Main()

    {

        Test();

    }

    public static BaseGeneric<TBase> Test<TBase>() where TBase : Base

    {

        return (new Blah() as BaseGeneric<TBase>);

    }

}

​

public class Base 

{

}

​

public class Derived : Base

{

}

​

public class BaseGeneric<TBase> where TBase : Base

{

}

​

public class Blah : BaseGeneric<Derived>

{

​

}