Dice the yellow onion and red bell pepper. Mince the garlic cloves. Open and thoroughly rinse and drain both cans of beans. Gather all your spices.

Heat olive oil in a large Dutch oven or heavy-bottomed pot over medium-high heat. Add the ground beef and cook, breaking it up with a spoon, until fully browned. Drain off any excess fat and set the beef aside.

Reduce heat to medium. Add the diced onion and bell pepper to the pot. Sauté for 5-7 minutes, stirring occasionally, until softened. Add the minced garlic and cook for another minute until fragrant.

Stir in the tomato paste and cook for 1-2 minutes, allowing it to slightly darken and deepen in flavor.

Add the chili powder, ground cumin, smoked paprika, dried oregano, cayenne pepper (if using), salt, and black pepper to the pot. Cook, stirring constantly, for 1 minute to 'bloom' the spices.

Return the browned ground beef to the pot. Add the undrained diced tomatoes, crushed tomatoes, beef broth, rinsed and drained kidney beans, pinto beans, unsweetened cocoa powder (if using), and apple cider vinegar.

Stir everything well to combine. Bring the chili to a gentle boil, then reduce the heat to low, cover partially, and let it simmer for at least 60-90 minutes. Stir occasionally to prevent sticking and ensure even cooking. The longer it simmers, the more the flavors will meld and deepen.

After simmering, taste the chili and adjust seasonings as needed. You might want to add more salt, pepper, or a pinch more cayenne for heat.

Ladle the hot chili into bowls and serve immediately with your favorite garnishes such as shredded cheddar cheese, a dollop of sour cream, sliced green onions, diced fresh jalapeños, or crushed tortilla chips.