In a large Dutch oven, heat over medium heat and add diced bacon. Cook until crispy, about 5–7 minutes. Transfer bacon to a paper towel-lined plate, leaving grease in the pot.

Lower the heat slightly and melt butter in the same pot. Add diced onion and sauté for 5–7 minutes, until soft and translucent. Incorporate minced garlic and cook for an additional minute.

Sprinkle flour over the sautéed onions and stir well. Cook for 2 minutes, stirring constantly to eliminate raw flour taste, forming a roux.

Slowly whisk in chicken broth, scraping the pot's bottom. Increase heat to medium-high and bring to a gentle simmer for about 3–5 minutes.

Add cubed Russet potatoes to the simmering broth. Lower the heat, cover, and cook for 15–20 minutes or until fork-tender.

Once potatoes are cooked, gently mash some against the pot's sides for thickness while leaving chunks for texture.

Pour in heavy cream and add shredded cheddar cheese. Stir until the cheese melts, taking care not to boil. Season with salt and black pepper.

Ladle the soup into bowls, topping with reserved crispy bacon, additional cheese, and chopped green onions.