Cook your scrubbed potatoes until tender, about 10 minutes in the microwave or 45 minutes in the oven at 350°F. Cool slightly and chop or mash.

In a large pot over medium heat, cook the bacon until crispy, about 5-7 minutes. Transfer to a paper towel-lined plate, leaving drippings in the pot. Crumble and set aside.

Add unsalted butter to the bacon drippings and let it melt. Add minced garlic and chopped onion, cooking for 3-4 minutes until translucent.

Sprinkle in the all-purpose flour, stirring to combine. Cook for 1-2 minutes until it takes on a light golden color.

Gradually whisk in low-fat milk, half and half, and chicken stock. Bring to a gentle simmer over medium heat for about 5 minutes.

Add the prepared potatoes to the pot, stirring thoroughly. Allow it to simmer for another 5 minutes.

Sprinkle in salt, garlic salt, black pepper, and both kinds of cheddar cheese. Stir until the cheeses melt completely.

Ladle the soup into bowls, topping each with sour cream and fresh chives. Serve hot.