Fluent NHibernate Select Max of Count Grouped by property

I’d like to get the max of the count of some grouped by query with Projections or Subqueries.
Is it possible?

     AEntity aAlias = null;
     BEntity bAlias = null;
     var cntQuery = await _session.QueryOver<AEntity>()
        .Left.JoinAlias(pv => pv.BEntity, () => bAlias)
        .Select(
            Projections.Group<AEntity>(e => e.Id),
            Projections.Count(Projections.Property<AEntity>(x => x.Id)))
        .ListAsync(ct);

So this returns something like this:

+----------------------------------------+-------+
|                   id                   | Count |
+----------------------------------------+-------+
| "af517a65-18c2-4e9f-9df6-a537cc5c9c92" |     5 |
| "48bf681d-2ccd-4df8-b0e5-b2c3f418e3d0" |     1 |
| "c0699258-9f2b-4ce6-a895-91d759cbde29" |     3 |
| "0959f6b4-b365-43fa-aede-25df327a27d1" |     2 |
+----------------------------------------+-------+

I need the max of these but wouldn’t like to use:

• order desc and take
• LINQ after ListAsync
• SQL query

var results = session.QueryOver<AEntity>()
        .Left..JoinQueryOver(pv => pv.BEntity, () => bAlias)
        .SelectList(list => list
            .SelectGroup(pv => pv.Id)
            .SelectCount(() => pv.Id)
        )
        .List<object[]>();