Preheat the oven to 400°F (200°C).
Cut the Velveeta into cubes and spread them in the bottom of a 9×13-inch baking dish.
Drain the ROTEL, black beans, and corn, then add them to the dish with the cheese and stir to combine.
In a small bowl, mix the salt, garlic powder, cumin, and chili powder.
Season both sides of the chicken breasts with the spice mixture and place them flat on top of the cheese and vegetable mixture.
Cover the baking dish tightly with foil and bake for 45 minutes.
Remove the foil and bake an additional 5–10 minutes, or until the chicken registers 165°F (74°C) and is cooked through.
Carefully remove the chicken from the dish, stir the melted cheese and vegetable mixture until smooth, then return the chicken to the dish on top of the queso.
Spoon queso over the chicken and garnish with chopped cilantro and green onions before serving.