Heat the butter and oil in a large pot over medium-high heat until melted.
4 Tablespoons unsalted butter, 1 Tablespoon oil
Sauté the diced onion for 2 to 3 minutes until softened.
1 onion
Add the minced garlic, and cook for about 1 minute or until it becomes fragrant.
5 cloves garlic
Stir in the diced mushrooms and 2 teaspoons of chopped thyme. Cook for 5 minutes, allowing the mushrooms to soften.
1 1/2 pounds fresh brown mushrooms, 4 teaspoons chopped thyme
Sprinkle the mushrooms with flour, mix well, and cook for an additional 2 minutes to eliminate the raw flour taste.
1/4 cup all-purpose flour
Pour in the low-sodium chicken broth or stock, mixing thoroughly to incorporate the flour. Bring the mixture to a boil.
5 cups low-sodium chicken broth or stock
Once it's boiling, reduce the heat to low-medium, and season the soup with salt and black cracked pepper. Adjust the seasoning to taste.
1-2 teaspoons salt, 1/2-1 teaspoon black cracked pepper
Cover the pot and let the soup simmer for 10-15 minutes, stirring occasionally, until it thickens.
Reduce the heat to low, and stir in the heavy cream (or half and half). Be sure not to let the soup boil; just let it gently simmer.
1/2 cup heavy cream or half and half
Adjust the salt and pepper to taste. Mix in chopped fresh parsley and the remaining thyme.
Chopped fresh parsley and thyme to serve
Serve the creamy mushroom soup warm, garnished with additional parsley and thyme if desired.