Preheat oven to 400°F (200°C).
In a small bowl, mix ½ teaspoon salt, ½ teaspoon garlic powder, ½ teaspoon cumin, and ½ teaspoon chili powder.
Pat the 2 lbs boneless, skinless chicken breasts dry with paper towels. Season both sides of each breast evenly with the spice mixture.
Arrange the chicken breasts in a single layer (not overlapping) in a large casserole dish.
Drain the 10 ounces ROTEL tomatoes with green chiles and spoon the drained ROTEL evenly over the chicken breasts to cover them.
Sprinkle ¾ cup shredded cheddar cheese evenly over the ROTEL-covered chicken.
Cover the casserole dish tightly with foil and bake for 25 minutes.
Remove the foil and bake an additional 5–10 minutes, or until the chicken reaches an internal temperature of 165°F (74°C).
Remove from the oven and let the dish rest for a few minutes.
Top with freshly chopped cilantro and/or freshly chopped green onions, then serve warm.