Slice the mushrooms.

Saute the sliced mushrooms in a non-stick skillet sprayed with cooking spray until browned.

Set the sauteed mushrooms aside.

In a saucepan, mix the milk powder, onion flakes, cornstarch, chicken bouillon cube, basil, thyme, and black pepper.

Add 2 cups of cold water to the saucepan and stir constantly over medium heat until the mixture thickens.

Add 1 to 1 1/2 cups of mashed potatoes and blend well into the soup.

Add about 1 cup of additional water to thin the soup to your desired consistency.

Add the sauteed mushrooms to the soup.

Serve the soup in bowls and top with a spoonful of shredded cheddar cheese.