Prepare all ingredients before you start cooking.
In a large Dutch oven over medium heat, cook the chopped bacon until it becomes crispy and browned.
Remove the bacon from the pot and let it rest while keeping the drippings in the pot.
Add unsalted butter and diced onion to the pot. Sauté until the onions are soft, about 3 to 5 minutes.
Incorporate the minced garlic and sauté until fragrant, around 30 seconds.
Sprinkle the flour over the onion mixture, stirring to achieve a smooth consistency.
Introduce the diced potatoes, chicken broth, milk, heavy cream, salt, pepper, and ancho chili powder. Mix them well.
Increase the heat to bring the mix to a boil, then cook until the potatoes are fork-tender, roughly 10 minutes.
Once the potatoes are tender, carefully blend about half of the soup until smooth, either in a blender or using an immersion blender.
Return the blended soup to the pot and stir in sour cream and reserved bacon pieces.
Allow the soup to simmer for another 15 minutes before serving.
Serve hot, garnished with your choice of extra sour cream, bacon bits, cheddar cheese, or chives.