Preheat your oven to 400°F (200°C).

In a large skillet, heat the vegetable oil over medium heat. Add the chopped onion and garlic, sautéing until the onion is translucent, about 3-4 minutes.

Add the ground beef to the skillet, cooking until browned and fully cooked, about 5-7 minutes. Drain any excess fat.

Stir in the black beans, diced tomatoes with green chilies, chili powder, cumin, salt, and black pepper. Simmer for 5 minutes, allowing the flavors to meld.

In a separate bowl, combine the corn muffin mix, milk, and egg, stirring until just combined.

Spread the beef mixture evenly in a greased 9-inch pie dish. Pour the corn muffin batter over the top, spreading it gently to cover the beef mixture.

Sprinkle the shredded cheddar cheese and jalapeños (if using) over the corn muffin batter.

Bake in the preheated oven for 20-25 minutes, or until the top is golden brown and a toothpick inserted in the center comes out clean.

Let the tamale pie cool for 5 minutes before slicing. Garnish with fresh cilantro if desired.