自动映射器列表转换为int（计数）

I'm creating ViewModels in my MVC application. We are using automapper for domain model to view model conversion. My question is I keep getting a circular reference error when doing ajax stuff in MVC (seems like it's the JavaScriptSerializer that's causing problems), so instead of getting back a list of Projects, I just need the count (because that's all my view model needs). Here is a sample of the hierarchy. Thanks in advance for any advice!

public class ProjectViewModel
{
    public int ProjectID { get; set; }
    [Required]
    [UIHint("Project Name")]
    public string Name { get; set; }
    public ICollection<ProjectGroupViewModel> ProjectGroups { get; set; }
}

public class ProjectGroupViewModel
{
    public int ProjectGroupID { get; set; }

    [Required]
    public string Name { get; set; }
    //THIS is what I Want to have as int ProjectCount
    public ICollection<ProjectViewModel> Projects { get; set; }
}

public class ProjectGroupViewModel
{
    public int ProjectGroupID { get; set; }

    [Required]
    public string Name { get; set; }
    //THIS is what I Want to have as int ProjectCount
    public int ProjectsCount { get; set; }
}

AutoMapper.Mapper.CreateMap<ProjectGroup, ProjectGroupViewModel>()
    .ForMember(x => x.ProjectsCount, o => o.MapFrom(x => x.Projects.Count()))