Season both sides of the chicken breasts liberally with salt and pepper. Combine the chipotle chili powder, cumin, and garlic powder in a small bowl, then sprinkle the spice mixture evenly over both sides of the chicken.
Heat a large non-stick skillet over medium-high heat. Add the chicken to the hot skillet and cook for 3 to 5 minutes without moving it until the bottom is well-browned or blackened.
Flip the chicken, cover the skillet with a lid, and reduce the heat to medium. Cook for 5 to 7 minutes until the chicken is fully cooked through. Transfer the chicken to a cutting board to rest for 5 minutes, then slice into bite-sized pieces.
Prepare frozen cauliflower rice according to the package directions. If using fresh cauliflower rice, place it in a large skillet with 1 tablespoon of water, cover, and cook over medium heat until tender.
Drain any excess liquid from the cauliflower rice, then toss it with approximately 1 tablespoon of lime juice and ¼ teaspoon of salt.
Stir together the mashed avocado, approximately 1 tablespoon of lime juice, and ¼ teaspoon of salt in a small bowl.
Divide the cauliflower rice among four serving bowls. Top with the chicken, shredded lettuce, guacamole, and optional pico de gallo. Garnish with lime wedges if desired and serve the burrito bowls warm.
