Heat the butter olive oil in a sauce pot, add the celery and onion and sauté for 6 to 7 minutes, until onions become translucent and celery gets softer.
Add spinach to the celery and onions and sauté for 30 seconds to 1 minute, until it becomes wilted and tender.
Mix rosemary, sage, salt, pepper, sugar, garlic, and chicken stock together. Add chicken stock and spices to celery onions and spinach. Cook for 5 minutes on low to medium heat, stirring occasionally.
Remove completely from the heat and add the cheese and bread. Mix until cheese is melted liquid is absorbed into the bread and stuffing looks consistent throughout. Finish by drizzling Roasted Walnut Oil on top (optional). Add more bread if needed to make stuffing drier.