1. In an 11- to 12-inch ovenproof frying pan (2 to 3 in. deep, 2 1/2- to 3-quart capacity) over high heat, stir onion, beef, chili powder, and cumin seeds until beef is crumbled and lightly browned, 6 to 8 minutes.
2. Add tomatoes (including juices), corn, and olives; bring to a boil, stirring occasionally. Add salt to taste.
3. Meanwhile, in a bowl, whisk together egg, egg white, 1/2 cup cheese, milk, cornmeal, baking powder, and 1/4 teaspoon salt until well blended (mixture will be thin). Pour evenly over hot meat mixture. Sprinkle evenly with remaining 1 cup cheese.
4. Bake in a 400° regular or convection oven until the top feels firm when lightly touched, about 15 minutes. Scoop out servings with a large spoon. Add salt to taste.