Self referencing entity CRUD EF CORE

I have trouble to do a CRUD for self reference entity.

This is my entity:

public class Category
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }
    [Required]
    public string Name { get; set; }
    public virtual ICollection<Recipe> Recipes { get; set; } = new HashSet<Recipe>();
    public int? ParentId { get; set; }
    public virtual Category Parent { get;set; }
    public virtual ICollection<Category> Categories { get; set; } = new HashSet<Category>();
}

ModelBuilder:

modelBuilder.Entity<Category>()
    .WithMany(c => c.Categories)
    .HasOne(c => c.Parent)
    .HasForeignKey(c => c.ParentId);

My create logic:

public void Save(Category category)
{
    if(category.Parent != null && category.Parent.Id == 0)
    {
       category.Parent = null;
    }
    else
    {
        _db.Entry(category.Parent).State = EntityState.Unchanged;
    }
    _db.Category.Add(category);
    _db.SaveChanges();
}

Update logic:

public void Update(Category category)
{
    _db.Category.Update(category);
    _db.SaveChanges();
}

CategoryDto class:

public class CategoryDto
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int? ParentId { get; set; }
    public CategoryDto Parent { get; set; }
}

I am not able to save this object to database, because seems like Parent wants to be saved as well, getting that Name field is required.

Any ideas how CRUD should look like for a self referencing entity?

Any answers are appreciated.