Place the boneless skinless chicken breasts in the slow cooker. Ensure that the chicken is fully thawed before cooking.
Pour the chicken broth over the chicken.
Add the olive oil, onion powder, garlic powder, chili powder, cumin, drained diced tomatoes, salt, and black pepper.
Stir gently to combine the broth, tomatoes, oil, and seasonings around the chicken.
Cover the slow cooker and cook the chicken for approximately 4 hours, or until the internal temperature reaches 165°F.
Once the chicken is fully cooked, remove it from the slow cooker and transfer it to a plate or cutting board.
Shred or chop the chicken into bite-sized pieces, then set it aside.
Increase the slow cooker heat setting to high.
Add the rinsed and drained black beans and whole grain brown rice to the slow cooker.
Stir well, ensuring that the rice is mostly covered by the cooking liquid.
Cover and cook for 30 to 45 minutes, or until the rice is tender and the liquid has been mostly absorbed.
Return the shredded or chopped chicken to the slow cooker.
Stir until the chicken, rice, beans, tomatoes, and seasonings are evenly combined.
Sprinkle the shredded Colby Jack cheese evenly over the top.
Cover the slow cooker again and allow the cheese to melt completely.
Serve warm in bowls with desired toppings, such as green onions, fresh diced tomatoes, avocado, guacamole, sour cream, salsa, lime wedges, or tortilla chips.