Heat the olive oil in a large pot or Dutch oven over medium heat.

Add the onion, bell peppers, carrot, and zucchini. Cook for 6 to 8 minutes, stirring occasionally, until the vegetables begin to soften.

Stir in the garlic and tomato paste, and cook for 1 minute until fragrant.

Add the chili powder, cumin, smoked paprika, cinnamon, nutmeg, cayenne pepper if using, salt, and black pepper. Stir well to coat the vegetables in the spices.

Pour in the diced tomatoes, pumpkin puree, vegetable broth, and maple syrup. Stir until the pumpkin is fully mixed in and the chili is smooth.

Add the black beans, kidney beans, pinto beans, and corn. Bring the chili to a gentle boil.

Reduce the heat to low and simmer uncovered for 25 to 30 minutes, stirring occasionally, until the chili thickens and the flavors come together.

Stir in the apple cider vinegar and taste. Adjust seasoning with more salt, pepper, or chili powder if needed.

Ladle the chili into bowls and garnish with chopped cilantro and sliced avocado. Serve with tortilla chips or warm bread.