In a large pot over medium heat, cook bacon until it begins to crisp. Next, add onions and cook until they are translucent. Add garlic and cook for about 1 minute.
Add in one bag of collard greens at a time, using the bacon grease to wilt the greens. Add salt and pepper and red pepper flakes once greens have wilted.
Next, chicken stock add apple cider vinegar and bring to a boil.
After greens begin to boil, reduce heat to low and cover. Cook for at least one hour.
Enjoy!