Melt butter in a large pot or Dutch oven over medium heat. Add the diced onion and cook until softened, about 5-7 minutes. Add the minced garlic and cook for another minute until fragrant.

Sprinkle the flour over the onions and stir continuously for one minute to cook out the raw flour taste.

Slowly whisk in the chicken broth. Add the cubed potatoes, salt, and pepper. Bring to a boil, then reduce the heat, cover, and simmer for 15-20 minutes, until potatoes are tender.

Use an immersion blender to partially blend the soup until it reaches your desired consistency. For a chunkier soup, blend less.

Reduce heat to low and stir in the heavy cream and sour cream. Warm through gently, but do not boil. Taste and adjust seasoning.

Serve hot, garnished with crumbled bacon, cheddar cheese, and chives, if desired.