Preheat your oven to 350°F. Grease a 9x13-inch baking dish and set it aside.

Warm a large skillet over medium heat. Add the ground beef and chopped onion.

Cook and stir until the beef is browned and the onion is soft, about 5–7 minutes. Drain off excess fat.

Stir in the black beans and diced tomatoes with green chilies. Add the chili powder, cumin, garlic powder, salt, and black pepper. Simmer for 4–5 minutes.

In a medium bowl, whisk together the cornmeal, milk, and egg until combined. Let the batter sit for 2–3 minutes.

Pour half of the cornmeal mixture into the prepared baking dish, spreading it out evenly.

Spoon the beef and bean mixture over the cornmeal layer, smoothing it to the edges.

Pour the remaining cornmeal batter over the beef, trying to cover the filling evenly.

Sprinkle the shredded cheddar cheese and optional sliced black olives on top.

Bake for 30–35 minutes, until the top is golden and the pie is set. A toothpick should come out mostly clean.

Let the tamale pie cool for about 10 minutes before slicing. Garnish with chopped cilantro before serving.