Querying with methods in EF Core?

I'm trying to figure out a way to use methods in a SELECT query in EF Core to reduce the amount of code that is rewritten over and over again. Instead a simple method could be used to query that piece of data. The query looks like so...

 var users = await DbContext.Users.Where(user => user.Id == 1)
                                   .Select(user => new UserDTO
                                   {
                                       Id = user.Id,
                                       Name = user.Name,
                                       Unavailable = user.Tasks
                                                       .Any(task => task.HasTasksToday()),
                                   }).ToListAsync();

The HasTasksToday() code looks like so...

    public bool HasTasksToday()
    {
        return Tasks.Any(task => task.StartedAt.Date == DateTime.Now.Date);
    }

The problem is I get a...

...could not be translated. Either rewrite the query in a form that can be translated...

...error.

I know that using IQueryable may work for this but I am unsure how that would even happen in the select statement as I know only how to use IQueryable on the Users entity.