Pat the chicken dry and trim any fat, then cut into bite-sized pieces.
Sprinkle 2 to 3 tablespoons taco seasoning over the chicken and toss gently to coat (use about 2½ tablespoons if you like).
Heat 2 tablespoons olive oil in a large nonstick pan over medium heat. Add the seasoned chicken and cook until mostly cooked through, about 5–7 minutes.
Cube and soften the cream cheese in the microwave, then add it to the pan with the chicken and stir until the mixture is smooth and the chicken is fully cooked. Transfer the chicken and cream cheese mixture to a plate and cover to keep warm.
With the pan still over medium heat, add the uncooked rice and toast, stirring, for about 1 minute without liquid.
Add the salsa, taco sauce, and chicken broth to the toasted rice. Bring to a boil, then reduce heat to low or medium-low and cover.
Simmer, stirring occasionally (every 7–8 minutes), until the rice is tender, about 15–20 minutes. If the rice cooks too quickly add a splash more broth; if it seems too wet raise the heat slightly. Remove from heat and let sit, covered, for 3–4 minutes.
Return the pan to low heat, stir in the drained black beans and frozen corn, and warm through.
Add the reserved cream cheese and chicken mixture back to the pan and gently stir to combine. Remove from heat and stir in the shredded Cheddar until melted.
Taste and season with salt and pepper as needed, then divide among plates and top with sliced or diced avocado and any other desired toppings.
