Heat the olive oil in a large pot over medium heat until warm. The chopped onion and minced garlic are cooked until softened and aromatic, about 3-4 minutes.
Add the chilli powder, cumin, smoked paprika, salt, and black pepper, stirring to combine. Cook for 1 minute to let the spices toast and enhance their fragrance.
Stir in the pumpkin purée, black beans, kidney beans, diced tomatoes with their juices, and vegetable broth. Stir everything together until well combined.
If using, add the maple syrup and diced jalapeño. Stir to mix evenly.
Bring the mixture to a soft boil, then lower the heat to a simmer.
Cover the pot and let it simmer for 20-30 minutes, stirring occasionally to avoid sticking.
Before serving, taste the chilli and modify the seasonings to your preference. If desired, stir in the lime juice for added brightness.
Ladle the chilli into bowls and garnish with your favourite toppings, such as fresh cilantro, avocado slices, or vegan sour cream.