Melt 2 tablespoons of butter in a large Dutch oven or soup pot over medium-high heat. Add sliced cremini mushrooms and sear undisturbed for 4 minutes until deeply browned, then stir and cook 2 minutes more. Transfer half the mushrooms to a plate for garnish.

Melt remaining 1 tablespoon butter in the pot. Add diced onion, carrots, and celery. Sauté for 5 to 6 minutes until vegetables begin to soften and onions turn translucent.

Stir in minced garlic, thyme, sage, salt, and black pepper. Cook for 1 minute until fragrant. Sprinkle flour over the vegetables and stir continuously for 1 to 2 minutes to cook out raw flour taste.

Slowly pour in broth while whisking steadily to dissolve the flour roux without lumps. Add rinsed wild rice blend and bring to a vigorous boil.

Reduce heat to low, cover with a tight-fitting lid, and simmer gently for 40 to 45 minutes until the wild rice grains are tender and split open.

Remove lid and stir in heavy cream and the reserved browned mushrooms. Simmer uncovered for 3 to 5 minutes until soup is luxuriously thick and velvety.

Taste and adjust salt and cracked black pepper as desired. Ladle into warm bowls, garnish with fresh parsley and extra cracked pepper, and serve warm!