optional garnish: additional cheddar cheese, green onion, bacon
Method
Heat oil in a large stockpot or dutch oven and saute onion for 5 minutes. Add garlic and cook for another 2 minutes. Add potatoes, broth and water, and bring to a boil. Reduce heat to medium and cook about 20 minutes, or until potatoes are tender. Remove 2 cups of potatoes and set aside. Mash the remaining potatoes with a potato masher right in the pot.
In a small saucepan, melt the 3 tablespoons butter. Stir in the flour and cook for 2 minutes. Whisk in milk. Bring to a boil and allow mixture to simmer until thickened. Stir mixture into your stockpot withe the mashed potatoes.
Bring to a boil and reduce heat to a low simmer. Stir reserved cubed potatoes back into the pot.
Stir in parsley, cheese, and sour cream. Season to taste with salt and pepper.