Prepare the Base: In your slow cooker, Instant Pot, or large pot, combine the dry wild rice blend, diced chicken breasts, chopped carrots, celery, and shallots. Pour in the low-sodium chicken broth, and add fresh thyme, sage, crushed red pepper flakes, and a generous pinch of salt. For the stove method, sauté the vegetables in a bit of butter first for enhanced flavor.

Cook the Soup: If using a slow cooker, cover and cook on low for 5–6 hours or high for 2–3 hours. For the Instant Pot, seal the lid and cook on high pressure for 15 minutes, then perform a quick release. On the stovetop, bring the mixture to a simmer, then cover and cook for about 40–45 minutes, or until the rice is tender and the chicken is cooked through.

Shred the Chicken: Once the cooking time is complete, carefully remove the chicken breasts from the pot and use two forks to shred the chicken into bite-sized pieces. Return the shredded chicken to the pot, allowing it to mingle with the rich flavors of the creamy wild rice chicken soup, making it even heartier.

Add Creamy Ingredients: Stir in the heavy cream or whole milk and grated Parmesan cheese if you're using it. Gently fold in the fresh baby spinach or kale for a pop of color and nutrition. Allow the soup to warm through on low for about 5–10 minutes, ensuring it’s heated but not boiling, which keeps the cream from curdling.

Roast the Mushrooms: While the soup simmers, preheat your oven to 425°F. Toss mixed mushrooms with melted butter, minced garlic, and fresh rosemary in a baking dish. Roast for 25–30 minutes, stirring halfway through, until the mushrooms are golden and crispy.

Serve the Soup: To serve, ladle the creamy wild rice chicken soup into bowls and top with a generous portion of the roasted mushrooms. If desired, sprinkle with additional Parmesan cheese and fresh parsley for a touch of brightness.