Preheat your oven to 375°F (190°C).
In a large skillet over medium heat, brown the ground beef and chopped onion until the meat is fully cooked, about 5-7 minutes. Drain any excess fat.
Stir in the black beans, corn, diced tomatoes with green chilies, and taco seasoning. Cook for an additional 3-4 minutes, ensuring everything is well combined. Season with salt and pepper to taste.
In a mixing bowl, combine the sour cream and half of the shredded cheddar cheese. Set aside.
Spread the meat mixture evenly in a greased 9x13 inch baking dish. Layer the sour cream and cheese mixture on top of the meat.
Unroll the crescent roll dough and lay it over the sour cream mixture, pinching the seams to seal. Sprinkle the remaining cheddar cheese on top, and if desired, add the sliced jalapeños.
Bake in the preheated oven for 25-30 minutes, or until the crescent dough is golden brown and the cheese is bubbly.
Allow the casserole to cool for a few minutes before serving. Enjoy your hearty John Wayne Casserole!