Heat olive oil in a large pot over medium heat. Add the diced onion and cook until softened, about 5 minutes.
Add minced garlic and cook for 1 minute more until fragrant.
Stir in chili powder, cumin, smoked paprika, and cayenne pepper. Cook for 1 minute to toast the spices.
Add chicken breasts to the pot and pour in the chicken broth. Bring to a boil, then reduce heat and simmer for 20 minutes, or until chicken is cooked through.
Remove chicken from the pot and shred using two forks. Return shredded chicken to the pot.
Add black beans, kidney beans, diced tomatoes, tomato sauce, salt, and black pepper. Stir well and simmer for 20–25 minutes to allow flavors to meld.
Serve hot, garnished with fresh cilantro if desired.
Notes
Perfect for meal prep—this chili tastes even better the next day!