Heat the olive oil in a large Dutch oven or heavy pot over medium-high heat.
Add the chopped onion and sauté for about 2 minutes, until softened.
Add the ground beef and cook for about 5 minutes, breaking it up as it browns. Drain any excess fat.
Stir in the minced garlic and cook for 30 seconds until fragrant.
Add the chili powder (if using), cumin, brown sugar, oregano, salt, pepper, and tomato paste. Stir well to combine.
Pour in the beef broth, scraping up any browned bits from the bottom of the pot.
Stir in the fire-roasted crushed tomatoes, kidney beans, and pinto beans.
Bring the chili to a boil, then reduce heat to low. Cover and simmer for 1–2 hours, stirring occasionally.
In the last 30 minutes, uncover the pot to allow the chili to thicken.
Serve hot with your favorite toppings like shredded cheddar cheese, sour cream, green onions, or cilantro.