Start by dicing your chicken into bite-sized pieces and chopping all your veggies. Rinse the wild rice under cold water to remove any excess starch. Taking a few minutes to prep everything now will make cooking later a breeze!
Melt some butter in a large pot over medium heat. Add the diced chicken, cooking until it’s lightly browned but not fully cooked through. Remove the chicken and set it aside. Toss in the carrots, celery, and onion next, sautéing until they soften and release their aromatic goodness.
To the softened veggies, add the wild rice and mushrooms. Stir everything together, then pour in the chicken broth. Return the chicken to the pot, season with salt and pepper, and bring everything to a boil. Lower the heat and simmer for about 30 minutes until the rice is tender and the flavors meld beautifully.
While the soup simmers, prepare the creamy base in a separate pan. Melt the remaining butter, then whisk in the flour to form a smooth paste. Gradually add chicken broth, whisking constantly to avoid lumps. Stir in the heavy cream, cooking until the mixture thickens into a smooth, velvety sauce.
Pour the creamy roux into the soup mixture, stirring well to combine. Allow the soup to simmer for a few more minutes, letting the flavors marry. For a pop of freshness, garnish with chopped parsley or thyme before serving.