Preheat oven to 400 degrees F.
Making the Filling: In a large skillet over medium-high heat, warm the oil until hot. Add the onion, green pepper and jalapeños, and cook, stirring occasionally, until softened, about 10 minutes. Transfer to a bowl and set aside.
Reduce the heat to medium and add the ground beef to the pan. Cook, stirring occasionally to break up the meat, until browned, 5 to 10 minutes. Once the meat is browned, add the onion mixture back to the pan. Stir in the corn, diced tomatoes, tomato paste, chili powder, cumin and salt. Stir well to ensure that the spices and the tomato paste are evenly distributed. Bring to a simmer, then reduce the heat to low and simmer for 20 minutes. Remove from the heat and let stand while preparing the cornbread topping.
Make the Cornbread Topping: In a large bowl, whisk together the cornmeal, flour, sugar, baking powder, baking soda, and salt. In a medium bowl, whisk together the buttermilk, eggs, and melted butter. Add the buttermilk mixture to the dry ingredients and use a rubber spatula to gently mix it together, taking care not to overmix the cornbread batter.
Assemble & Bake the Pie: Stir the olives (if using) and shredded cheese into the beef mixture and pour it into a 9x13-inch baking dish, smoothing the top. Pour the cornbread batter over the filling, using a spatula to spread it into an even layer. Bake for 15 to 20 minutes, or until the top is golden brown and a knife inserted into the center comes out clean. Allow the pie to rest for 15 minutes before serving.