No one does Baked Potato Soup like Houlians. They use instant mashed potato flakes for a special flare. Source Pittsburgh Post-Gazette.

1 1/2 lbs. baking potatoes
1/4 lb. Butter
2 C. Yellow onion — diced
1/3 C. flour
5 C. Water
1/4 C. low sodium chicken base
1 C. Instant potato flakes
3/4 tsp. dried basil
1/2 tsp. Tabasco sauce
1 C. heavy cream
1 C. milk
Salt — to taste
White pepper — to taste

Preheat oven to 400. Prick washed potatoes & bake until a fork pierces to the center easily. Remove potatoes from oven & allow to fully cool. Remove skin & cut potatoes into 1/2″ cubes. Set aside. Melt butter in a large saucepan. Add onions & saute over low heat for 10 minutes or until onions are translucent. Don’t allow onions to burn. Add flour to onions & butter and cook 4 – 5 minutes, stirring well until flour is absorbed. In a separate container, combine water, chicken base, potato flakes & seasonings. Stir or whisk thoroughly to eliminate lumps. Add slowly to onion mixture, stirring constantly so no lumps form. Increase to medium heat & continue cooking until the soup begins to gently simmer. Add milk & cream, stirring until smooth & lightly thickened. Simmer for 15 minutes. Do not boil. Soup should just simmer lightly. Add cubed baked potatoes & Stir to combine. Remove from heat & serve. Top each serving with grated Cheddar cheese, sliced scallions & bacon pieces.