Next, in a mixing bowl, whisk together the flour and milk.
Then, in a medium saucepan over medium heat, combine the chicken broth, mushrooms, garlic powder, onion powder, and salt and pepper. Bring to a low boil and let simmer for 2-minutes.
After that, add the milk and flour mixture to the saucepan and use whisk everything together.
Last, let the soup simmer until it reaches your desired thickness. Let it cool and use it or store in a sealed container in your fridge.
The calories listed are based on the ingredients and represent the entire 10-ounce cream of mushroom soup. Actual calories may vary. The soup substitute will hold for 3 to 5 days in your fridge in a sealed container.