Add the olive oil to a large heavy-bottomed stock pot set over medium-low heat then add
the onions, garlic chipotles in adobo, cumin, oregano, ancho chili powder and 1
teaspoon salt, and cook until the onions are translucent, about 10 minutes.
Increase the heat to medium, add the beer and cook until reduced by half, about 5 minutes.
Stir in the tomatoes, pumpkin purée, vegetable stock, black beans, kidney beans, and pinto beans and
reduce the heat to low.
Simmer the chili for one hour then stir in the brown sugar. Taste and season it with salt and pepper.
When ready to serve, top the chili with avocado, sour cream, cheese and cilantro.