In a small bowl, whisk together chili powder, cumin, salt, pepper and cayenne until combined. Take half of the seasoning mixture and set it aside.
Take the other half, and sprinkle it evenly over both sides of the chicken breasts. Heat 2 tablespoons oil in a large skillet over medium-high heat until shimmering. Add chicken and cook for 3 minutes per side, or until the chicken is cooked through and no longer pink inside. Remove from heat and set aside for 10 minutes. Then slice into thin strips and set aside.
Meanwhile, return the skillet to the heat and add the remaining 2 tablespoons of oil. Add the red onion, tomatoes, corn and garlic and saute for 5 minutes, stirring occasionally. Add the cream cheese and milk gradually, stirring constantly until the cheese melts completely. (And also be sure that they cheese does not burn on the bottom of the skillet.) Stir in the remaining seasoning mixture, black beans, and cilantro until combined. Season with additional salt and pepper if needed.
Remove from heat, then gently stir in the avocado and pasta. Serve immediately with additional toppings if desired.