Bake potatoes for about 1 hour in a 350-degree oven. Remove from oven, cool, peel and cut into cubes.
Rinse half the bag of collard greens and drain in a colander, leaving some water clinging to the leaves. (Save remainder of collards for another recipe.) Place collards into a microwave-safe container with a lid (vented) and micro cook on high for about 10 minutes, stirring at the halfway point for even cooking. Remove from microwave oven and place collards in colander to cool and drain. When collards are cool enough to handle, mass them on a cutting board and chop a bit more finely. Set aside. (You may omit this step of extra chopping, but it makes a more refined-looking soup.)
In a large stockpot over medium heat, melt butter and sauté onion for about 7 minutes, until tender. Add flour and Seasoning blend, stirring well to combine; it will look pasty. Allow mixture to cook for another minute, stirring occasionally.
Add broth, water, potatoes and collards and return to a boil. Cover, reduce heat and simmer for about 10 minutes. Uncover, mash potatoes in the soup with a potato masher (there will still be chunks remaining), add milk and heat through. Stir in cheese and serve.
This recipe is ideal for leftover baked potatoes.