Heat a few tablespoons of oil in a large Dutch oven or skillet over medium heat. Add the onions and jalapeño and cook until softened, 5 to 7 minutes. Add the garlic, chili powder, cumin, and sugar and stir until fragrant, 30 seconds to 1 minute. Add the tomatoes, tomato sauce, and stock. Season with salt and pepper. Bring to a gentle boil, then transfer to the bowl of a slow cooker. Add the corn, beans, and chicken thighs to the slow cooker. Cover and set on low for 6 to 7 hours (or high for 4 hours). Shred the cooked chicken using two forks (if using bone-in thighs, remove the chicken to shred; discard bones and return meat to the soup). Stir in a splash of heavy cream if desired. Season the soup with additional salt, pepper, and cayenne pepper, to taste. Serve with cheddar cheese, sour cream, tortilla chips, and cilantro for garnish. Recipe Notes You can use bone-in or boneless, skinless chicken thighs. I used bone-in for a rich, complex soup, but boneless are easy because you don't have to pull them out. This recipe can easily be doubled and frozen for another time. Transfer the cooled soup to a freezer-safe plastic bag labeled with recipe name and date. Press out excess air before sealing. Lay bags flat in a single layer in the freezer. (Once frozen, the bags can be stacked neatly.) To thaw, transfer to refrigerator overnight or set bag in a stockpot of warm water. Reheat in a saucepan over medium-low heat; season to taste.