Not-So-Corny Tamale Pie - cooking recipe

Ingredients

2 teaspoons vegetable oil, or as needed
1 small onion, chopped
1 1/2 pounds ground beef
1 (15 ounce) can pinto beans, rinsed and drained
1 (15 ounce) can black beans, rinsed and drained
1/2 cup shredded Mexican cheese blend (optional)
1 (14 ounce) can diced tomatoes with green chile peppers (such as RO*TEL(R))
2 (8.5 ounce) packages corn bread mix (such as Jiffy(R))
2/3 cup milk
2 eggs

Preparation

Preheat oven to 400 degrees F (200 degrees C).
Heat oil in a cast-iron skillet over medium-high heat; saute onion until lightly browned, 5 to 10 minutes. Add ground beef; cook and stir until beef is browned and crumbly, 5 to 10 minutes. Mix pinto beans and black beans into beef mixture.
Sprinkle Mexican cheese blend over beef-bean mixture; stir. Mix diced tomatoes with green chile peppers into beef-bean mixture.
Mix corn bread mix, milk, and eggs together in a bowl until batter is smooth. Spread batter over top of beef-bean mixture.
Bake in the preheated oven until a toothpick inserted in the center of the cornbread comes out clean, 15 to 20 minutes.