In a skillet over medium heat, cook the diced bacon until crispy. Transfer to a paper towel-lined plate to drain and set aside.

Place the diced potatoes, chopped onion, minced garlic, and cooked bacon into the slow cooker. Pour in the chicken broth and add dried thyme, dried parsley, salt, and black pepper. Stir to combine.

Cover the slow cooker and cook on low for 6-8 hours or on high for 3-4 hours, until the potatoes are tender.

About 30 minutes before the cooking time is complete, melt the butter in a saucepan over medium heat. Whisk in the flour until smooth and cook for about 1 minute.

Gradually whisk in the milk, continuing to stir until the mixture thickens into a creamy consistency.

Pour the roux into the slow cooker and stir to combine. Use a potato masher to gently mash some of the potatoes to achieve your desired soup thickness.

Stir in the shredded cheddar cheese and sour cream until fully incorporated and the cheese has melted. Taste and adjust seasoning as needed.

Ladle the soup into bowls and garnish with sliced green onions and additional bacon bits if desired.