Heat the olive oil in a large pot over medium heat, and add the diced onion. Sauté until it becomes translucent and fragrant, about 5 minutes, with a mild sizzle and sweet aroma filling the kitchen.
Add the minced garlic to the pot and cook for another 30 seconds until it becomes fragrant and slightly golden, enhancing its aroma.
Stir in the ground cumin, smoked paprika, and cayenne pepper if using, cooking for about 1 minute until the spices release their warm, earthy scent.
Add the diced pumpkin chunks to the pot, stirring gently to coat them with the spices and aromatic base. Cook for 5 minutes, allowing the pumpkin to start softening slightly and the mixture to smell sweet and spicy.
Pour in the vegetable broth and diced tomatoes with their juices. Bring the mixture to a gentle boil, listening for a lively bubbling sound.
Reduce the heat to low, cover partially, and simmer the chili for 20-25 minutes, stirring occasionally until the pumpkin is tender and the flavors meld, and the chili thickens slightly.
Add the rinsed black beans to the pot, stirring gently to incorporate them without breaking, and cook for another 5 minutes to heat through.
Season the chili with salt and pepper to taste, stirring well to distribute the seasoning evenly.
Once the chili is thick, fragrant, and the pumpkin is fully tender, turn off the heat and let it sit for a couple of minutes to settle
Serve the warm pumpkin and black bean chili in bowls, garnished with fresh cilantro if desired, for a cozy, colorful meal that showcases vibrant seasonings and hearty textures.