Heat 1 – 1½ tbsp oil in heavy Dutch oven or medium-sized stock pot over medium-high heat. Add 1 tbsp butter. Reduce heat to medium and add the onion, celery, and carrot. Cook the aromatics for 3-4 minutes, stirring frequently, until onion starts to become transparent. Add the minced garlic and mushrooms. Stir mixture briskly for 1-2 minutes longer, ensuring the garlic does not scorch. Stir in the chili powder, spices, salt, pepper, and cocoa. Add the browned meat to the pot.
Add the chicken or turkey stock, red wine, diced tomatoes with juice, tomato paste, tomato sauce, pumpkin purée, and brown sugar or maple syrup to the meat mixture. Stir. Add bay leaf. Cover and increase heat to bring mixture to a boil, then reduce heat to medium-low and cook slowly, stirring occasionally, until chili thickens, about 45-50 minutes. Add the drained and rinsed kidney beans. Simmer, partially covered, for 10-15 minutes more, until beans are heated. Remove and discard bay leaf and ladle chili into bowls. Top with a dollop of sour cream, green onions, and/or shredded cheese, if desired. Served with artisan bread or rolls or tortilla chips. This chili freezes well in airtight containers.