Preheat your oven to 400°F. Pierce each 4 large russet potatoes scrubbed clean several times ⅓ cup all-purpose flour over with a fork. Rub lightly with a little oil or 4 tbsp unsalted butter and place directly on the oven rack. Bake for 55–65 minutes, until completely tender when pierced with a knife. Set aside to cool for 10 minutes.

Line a baking sheet with aluminum foil, extending it up the sides to catch grease. Optionally place a wire rack on top for better airflow and crispier bacon. Lay strips in a single layer — close but not overlapping. No oil or extra seasoning needed.

Set oven to 400°F. You can start bacon in a cold oven as it preheats, or wait until fully preheated — both work. Use an external meat thermometer if your oven runs inaccurate. Start checking at 14–15 minutes. Thin-cut: 10–14 min. Standard-cut: 15–20 min. Thick-cut: 20–22 min. No need to flip. Check every couple of minutes after the first check — overdone happens fast. Pull bacon just before it looks done; it keeps cooking for a minute or two off the heat.

Add the 4 tbsp unsalted butter to the pot with the reserved drippings over 1 yellow onion finely diced heat. Once melted, add the diced stalks green onions thinly sliced and cook, stirring occasionally, until softened and translucent, about 5 minutes. Add the 3 cloves garlic minced and cook for 1 minute 1 ½ tsp kosher salt until fragrant.

Sprinkle the ⅓ cup all-purpose flour over the 4 stalks green onions thinly sliced and 3 cloves garlic minced mixture. Stir constantly for 1–2 minutes to cook out the raw flour taste — it will look pasty and thick. This is your roux and it's what makes the soup 1 cup sour cream full-fat and thick.

Slowly pour in the 4 cups chicken broth low-sodium, about 1 all-purpose flour at a time, whisking constantly after each addition to prevent lumps. Once all the broth is incorporated, pour in the 2 cups whole milk and whisk to combine. Bring the mixture to a gentle simmer over 1 yellow onion finely diced heat, stirring frequently, and cook for 5 minutes until slightly thickened.

Once the potatoes are cool enough to handle, cut them in half and scoop out the flesh. Roughly chop or break up the flesh into chunks — you want a mix of smaller pieces that will melt into the soup and larger chunks for texture. Discard the skins or save them for another use.

Add the 4 large russet potatoes scrubbed clean chunks to the soup and stir gently to combine. Reduce the heat to low. Add the 1 ½ tsp kosher salt, ½ tsp black pepper freshly ground, and 3 cloves garlic minced ¼ tsp garlic powder. Stir in the 1 cup sour cream full-fat until fully incorporated and smooth. Taste and adjust seasoning as needed. Let the soup simmer on low for 5 minutes to meld the flavors.

Stir in about half of the crispy 6 slices bacon cut into small pieces and half of the shredded cheddar directly into the soup. Stir until the 1 ½ cups sharp cheddar cheese freshly shredded is fully melted and the soup is velvety and smooth.