In a large pot, cook the bacon over medium heat until crispy. Remove, drain on paper towels, and crumble. Set aside.
In the same large pot, melt butter over medium heat. Add diced onion and celery then cook until soft, about 5 minutes. Stir in minced garlic and cook for an additional minute.
Sprinkle flour over the onions and garlic, stirring constantly for 1-2 minutes to create a roux. Sprinkle in all your seasonings and chicken buillon base mix until seasoning is evenly distributed and let cook for 1-2 minutes.
Slowly whisk in the chicken broth and bring to a simmer.
Stir in milk and heavy cream and add the diced potatoes. Bring to a boil, then reduce heat to medium and simmer for 15-20 minutes, or until the potatoes are tender.
Use a potato masher to lightly mash some of the potatoes in the pot, leaving some chunks for texture.
Stir in the shredded cheddar cheese, allowing the cheese to melt into the soup. Continue to cook until the soup thickens, about 5 minutes.
Stir in the sour cream, green onion, and half of the crumbled bacon. Adjust seasoning with additional salt and pepper if needed.
Ladle the soup into bowls and garnish with the remaining bacon, chopped chives, and extra cheese.
