c# List group by year then by month

Question

I have a class:

public class Item
{
    public string ItemId { get; set; }
    public DateTime Created { get; set; }
    public string Title { get; set; }
}

If I have a List how can I group the items per year and then by month?

Of course for year would be something like:

list.GroupBy(t=>t.Created.Year);

Answer 1

 list.GroupBy(t => new { Year = t.Created.Year, Month = t.Created.Month });