Wash and peel the potatoes, then dice them into bite-sized cubes. Boil in water for about 15 minutes until fork-tender, then drain.

In a large pot, combine chicken stock, yellow onion, salt, and black pepper. Add cold water and bring to a gentle simmer for 20 minutes.

In a saucepan, melt butter over medium-low heat. Gradually whisk in flour to form a roux, cooking for about 2 minutes.

Incorporate the roux into the simmering pot, whisking to blend. Cook for another 5 minutes until the soup thickens.

Stir in the heavy whipping cream and let the soup simmer another 20 minutes, stirring occasionally.

Fold in the cooked potatoes carefully, and heat through.

Ladle soup into bowls and top with cheddar cheese, crumbled bacon, and green onions. Serve immediately.