Coat a large nonstick skillet with vegetable cooking spray. Add the onion and cook over medium heat, stirring often, until the onions begin to color, about 5 minutes.
Add the garlic and cook 1 minute longer. Crumble the beef into the skillet.
Continue to cook over medium heat, stirring to break up any lumps of meat, until onion is lightly browned and the meat no longer pink, about 5 minutes.
Add the oregano, hot pepper, and cumin and cook, stirring, 1 minute.
Add the pinto beans, tomatoes, corn, 1/2 tsp of the salt, and 1/4 tsp of the pepper.
Reduce the heat to medium-low and simmer, uncovered and stirring occasionally, until thickened, about 15 minutes. Remove from the heat and set aside.
In a medium saucepan, bring 1 1/2 cups water to a boil.
In a medium heatproof bowl, combine the cornmeal with remaining 1/4 tsp salt and 1/8 tsp pepper.
Gradually whisk in 1/2 cup cold water until smooth.
Slowly stir the wetted cornmeal into the boiling water.
Cook over medium heat, stirring constantly, until the cornmeal is almost tender and the mixture is quite thick, 3 to 5 minutes.
Preheat the oven to 350° F.
Lightly coat a 9-inch-square baking dish with cooking spray.
Spoon the beef mixture into the dish.
Top with the cooked cornmeal and spread evenly to cover.
Sprinkle the cheese evenly over the top.
Bake until the cornmeal crust is set and dry throughout, the cheese is golden brown and the casserole is very hot at the center, 30 to 40 minutes.
Servings: 6