In a large skillet over medium heat, brown the ground beef with the chopped onion until the meat is fully cooked and the onion is tender. Drain any excess fat.

Stir in the black beans, corn, diced tomatoes, garlic powder, chili powder, cumin, salt, and pepper. Mix well and let it simmer for about 5 minutes.

Transfer the beef mixture to a greased slow cooker. Sprinkle the shredded cheddar cheese evenly over the top.

Unroll the crescent roll dough and cut it into strips. Lay the strips over the cheese, covering as much of the surface as possible.

Cover and cook on low for 4 to 5 hours or on high for 2 to 3 hours, until the dough is cooked through and golden brown.

Remove the lid and let it cool for a few minutes before serving. Garnish with fresh cilantro if desired.