Preheat oven to 375°F. Grease a 9x13-inch baking dish.
In a large bowl, mix hashbrowns, chicken, drained tomatoes, soup, sour cream, salsa, chili powder, cumin, salt, and pepper until combined.
Fold in 1/2 cup cheddar. Spoon mixture into the prepared dish and smooth the top.
Sprinkle remaining 1/2 cup cheddar over the casserole. Cover with foil.
Bake 25 minutes covered, then remove foil and bake 10–15 more minutes until bubbly and edges brown.
Let rest 5 minutes, then sprinkle cilantro if using and serve.