Spray a large saucepan with low-calorie cooking spray and place over a medium heat.
Add the onion and cook for 10 minutes, stirring, until slightly softened.
Add the garlic and cook for a further 3-4 minutes.
Add the mushrooms and thyme and cook for 5 minutes, until softened.
Add the vegetable stock and stock pot, and stir in.
Partially cover the saucepan with a lid and simmer over a low heat for 20 minutes.
Carefully transfer the hot soup to a food processor or use a handheld stick blender to blitz until smooth. You may need to do this in two batches.
Rinse out the saucepan and return the soup to the pan. Reheat over a low heat for a few minutes, if needed.
Remove from the heat and stir in the cream cheese with a wooden spoon or balloon whisk until it has completely dissolved.
Taste the soup and season with salt and pepper if needed.
Serve garnished with chopped flat leaf parsley.