Melt butter in a medium saucepan over medium heat.

Add the sliced onion and saute for 2 minutes, being careful not to brown.

Sprinkle flour over the onions and cook for about 5 minutes, stirring often.

Gradually add chicken broth to the onion and flour mixture, stirring constantly to avoid lumps.

Add diced potatoes, salt, dried basil, white pepper, black pepper, Tabasco sauce, and garlic salt to the saucepan.

Bring the mixture to a boil, then reduce heat to low and simmer for 20-25 minutes, or until potatoes are tender, stirring occasionally.

Stir in half-and-half and heat through, but do not boil.

Serve hot, garnished with grated cheddar cheese, cooked and crumbled bacon, a dollop of sour cream, and finely sliced green onion.