Heat 2 tablespoons butter in a medium pot over medium heat until it foams. Add orzo and toast until deeply golden in color. Add rice and stir 1 minute then add in 2 1/2 cups stock or broth. Cover and simmer over low heat for 18 minutes, fluff with a fork and add parsley. Reserve.
Heat a soup pot over medium to medium-high heat with EVOO, 2 turns of the pan, and melt in remaining 4 tablespoons butter. Add mushrooms and cook to deep brown, 15 minutes. Add garlic, thyme, rosemary, salt and pepper, and stir a minute or 2. Add in sherry and reduce 1-2 minutes; add in leeks, carrots, onions, celery and bay. Cover and sweat 5 minutes then add tomatoes and stir. Add remaining stock and turkey or chicken; let simmer to combine flavors.