Select from joined models

[iateadonut]

I'm doing this:

Project::search($request->get('search'))
            ->with('users');

which results in this query/subquery:
select * from (select projects.* from projects left join users on projects.user_id = users.id where projects.deleted_at is null group by projects.id, users.name, users.lastname) as projects;

I'm wondering how I can add a select to the subquery - I want to add users.lastname to the select portion of the subquery, like this:
select * from (select projects.*, users.lastname from projects left join users on projects.user_id = users.id where projects.deleted_at is null group by projects.id, users.name, users.lastname) as projects;