Step 1: First bake the potatoes in your oven at 400°F (or 204°C) until done. Then let them cool.
Step 2: While the potatoes are cooling, start melting butter in a large saucepan or pot then sauté the onions until they are light brown (also known as caramelized). Add flour to the onions and stir to make a roux.
Step 3: To the large saucepan or pot, add water, stock, cornstarch, instant mashed potatoes, and spices and bring to a boil. Once boiling, lower heat and let simmer for five minutes.
Step 4: Once cooled off, cut the baked potatoes in half lengthwise and using a large spoon scoop out the insides. Discard skin (or use them to make cheesy potato skins :).
Step 5: Chop the baked potato into chunks that are about 1/2-inch in size.
Step 6: Throw the chopped baked potato into the saucepan or pot and also add the half-and-half. Turn up the heat to bring the soup back to boiling, then reduce heat and let simmer for 15 minutes or until thick.
Step 7: Once cool enough to eat, fill up some bowls and add the toppings! You can add crumbled, crispy bacon, shredded cheddar cheese and/or chopped green onion.