Cut the cold 6-8 strips uncooked bacon* into small pieces. I like to use kitchen shears for this. Cook the pieces in a large Dutch oven or soup pot over medium heat until crisp and browned. Use a slotted spoon to remove the bacon and set aside, leaving the rendered fat in the pot.
Meanwhile, dice the 1 small (1 cup) yellow onion and mince the 3 teaspoons (3 cloves) garlic. Wash the 2 pounds (6 1/2 cups) cubed Yukon gold potatoes and peel if you'd like, I keep the skin on when using Yukon gold potatoes because it is very thin and not noticeable. Cut into ½-inch cubes.
Add 3 tablespoons butter and diced onion to the pot and cook over medium heat until the onions are soft, about 3–5 minutes. Stir in garlic and cook until fragrant, about 30 seconds. Sprinkle ⅓ cup all-purpose flour over the mixture and stir to coat onions.
Add cubed potatoes, 4 cups chicken stock or broth, 2 cups whole milk, 1/2 cup heavy cream, 1 1/2 teaspoons salt**, 1 teaspoon ground pepper, 3/4 teaspoon dried thyme and 3/4 teaspoon dried oregano. Stir to combine and bring to a boil. Cook at a boil until potatoes are tender, about 10 minutes.
Reduce heat to a simmer. Remove roughly half the soup (about 5 cups) and blend until smooth, use a blender carefully or an immersion blender. Return the pureed soup to the pot and stir in 1/2 cup sour cream, 2 cups sharp cheddar cheese and about half the bacon (less than half if you cooked 8 strips).
Simmer for 15 minutes before serving. Top with extra sour cream, bacon bits, cheddar cheese, and fresh chives.