This is a wonderfully comforting soup, perfect for those cooler evenings. It is a more or less healthy version of a classic that can be made more luxurious by substituting heavy cream for the milk. As always, make it your own and please add, subtract or substitute as you wish.
Heat a soup pot over medium heat. Add the butter and olive oil. Once the butter has melted, add the onions. Sweat the onions until they begin to wilt. Add the potatoes, garlic, and mushrooms and continue to cook until everything is softening and smelling wonderful. This whole step should take around 10 minutes or so.
Add the stock and the small bunch of Thyme. Bring up to a simmer and cook for about 5 minutes. Add the milk and return to a simmer.
Make a slurry out of the cornstarch with a little water. Add to the pot and bring just to a boil. Reduce the heat and stir frequently until the soup begins to thicken. If you want a thicker soup, add another batch of the slurry.
Add the chicken, mixed vegetables, and the seasoning. You could also add chopped fresh herbs along with or instead of the seasoning blend. Let everything simmer for a few minutes. Stir in the parsley and serve. Pass the croutons at the table.
Puff Pastry Croutons: Cut the pastry sheet into 1 inch squares (or whatever size you want) Lay on a parchment lined baking sheet (make sure they are not touching). Spray lightly with the Olive Oil spray and sprinkle with Coarse Salt and Freshly Ground Pepper. Bake in preheated 400 degree oven until puffed and golden, 9-10 minutes. Serve as a topping for the soup.