How to Make It
Chop scallions, separating green and white parts. Set aside.
Cook bacon in a large Dutch oven over medium, stirring occasionally, until crispy, 10 to 15 minutes. Using a slotted spoon, transfer to a plate lined with paper towels, leaving 2 tablespoons of bacon drippings in Dutch oven.
Add potatoes, onion, butter, garlic, and white scallion pieces to Dutch oven, and cook over medium until onions are slightly softened, 5 to 6 minutes. Add flour, salt, and pepper, and stir until all ingredients are coated. Cook, stirring constantly, 1 minute. Stir in broth until combined. Bring mixture to a boil. Then reduce heat to medium-low, and simmer until potatoes are tender, about 12 minutes.
Using a potato masher, lightly mash mixture, leaving some whole pieces of potato. Add white Cheddar and cream, stirring until cheese melts. Keep warm.
Ladle soup into bowls. Top servings with bacon, green scallion pieces, and yellow Cheddar.