In a medium bowl, whisk together Bisquick mix, milk and eggs; set aside.
Heat olive oil in a medium oven-proof skillet over medium high heat. Add ground beef and onion, and cook until browned, about 3-5 minutes, making sure to crumble the beef as it cooks; drain excess fat.
Stir in corn, black beans, taco seasoning and green chiles until well combined and heated through. Stir in Bisquick mixture.
Place into oven and bake until golden brown and cooked through, about 20-22 minutes. Sprinkle with cheese and bake until the cheese has melted, an additional 2-3 minutes.
Serve immediately, topped with romaine lettuce and tomato, if desired.