How to keep track of third property in Many-To-Many

        public int ReservationId { get; set; }
        public Reservation Reservation { get; set; }

        public int MenuId { get; set; }
        public int TimesOrdered { get; set; } <-- this property needs to keep track of how many times a menu has been ordered.
        public Menu Menu { get; set; }

        modelBuilder.Entity<Reservation>()
            .HasMany(x => x.Menus)
            .WithMany(x => x.Reservations)
            .UsingEntity<ReservationMenu>(
                rm => rm.HasOne(x => x.Menu).WithMany().HasForeignKey(k => k.MenuId),
                rm => rm.HasOne(x => x.Reservation).WithMany().HasForeignKey(k => k.ReservationId),
                rm =>
                {
                    rm.HasKey(p => new { p.MenuId, p.ReservationId });
                }
            );