In large saucepan or pot over medium-high heat, add about 1 tablespoon of oil. Add half the ground beef, spreading it evenly and cook so that it is browned. Remove from the pot, and repeat with another tablespoon and the rest of the ground beef. Remove all the beef from the pot.
Reduce the heat to medium and add another tablespoon of oil. Fry the diced onions about one minute until fragrant. Add the minced garlic and cook another minute. Add the tomato paste.
Add the chopped tomatoes, chipotle peppers and adobo sauce, cocoa powder, chili powder, cumin, brown sugar, and black pepper. Stir to combine, being sure to scrape the bottom of the pot to get the browned beef bits. Add the ground beef back to the pot and stir.
Add the beef broth and bring to a boil. Reduce the heat to low, place a lid on the pot, leaving it slightly uncovered, and let the chili simmer for 2 hours.
Taste the chili and add salt or more of the other seasonings as necessary. If the chili is too thick, add another ¼ cup of tomato sauce or beef broth.
Scoop into bowls and top with grated cheese, sliced avocado, sour cream, or chopped green onions. Serve with cornbread or tortilla chips.
Notes
If you want to add a can of beans to your chili, add another ½ cup of beef broth or tomato sauce to the pot so there is enough liquid to balance them.
Adjust the amount of chipotle peppers and chili powder to suit your desired level of spiciness.
Serve the chili with cornbread, bread sticks, tortilla chips, and/or a fresh salad!
Store leftovers in a food container in the fridge and reheat leftovers in the microwave or in a pot on the stovetop.