How to create an instance of a class which implements a contravariant interface and cast

I have the following:

public interface IWidgetUpdated<in TViewModel> where TViewModel : BaseWidgetViewModel, new()
{
    string SystemName { get; }

    Widget UpdateFromViewModel(TViewModel viewModel);
}


public abstract class BaseCcWidget<TViewModel> : IWidgetUpdated<TViewModel> where TViewModel : BaseWidgetViewModel, new()
{
    public abstract string SystemName { get; }

    public virtual Widget UpdateFromViewModel(TViewModel viewModel)
    {
        var widget = _widgetService.GetById(viewModel.Id) ?? new Widget();
        widget.Name = viewModel.DisplayName;
        if (widget.Id == 0) //Don't allow changing of widget type as set data might be incompatible.
            widget.SystemName = viewModel.SystemName;

        return widget;
    }
}

public class StaticContentWidgetViewModel : BaseWidgetViewModel 
{
    //Code removed for brevity
}

public class StaticContentWidget : BaseCcWidget<StaticContentWidgetViewModel>
{
    //Do implementations - removed for brevity
}

public IEnumerable<IWidgetUpdated<BaseWidgetViewModel>> GetUpdatableWidgets()
{
    var result = new List<IWidgetUpdated<BaseWidgetViewModel>>();

    var types = _typeFinder.FindClassesOfType(typeof(IWidgetUpdated<>));
    foreach (Type drType in types)
    {
        var obj = EngineContext.Current.ResolveUnregistered(drType); //Creates an instance of StaticContentWidget
        result.Add(obj as IWidgetUpdated<BaseWidgetViewModel>);
    }
    return result;
}

The issue I have is obj as IWidgetUpdated<BaseWidgetViewModel> doesn't work. I use the same code on covariant interfaces with success but it won't work in this instance.

Basically, I just need to be able to call obj.UpdateFromViewModel(). I've tried various casts without success.