1. Prepare the Hatch chiles: Start by roasting and peeling the chiles. Carefully remove the stems and seeds by slicing them open gently with a small knife or using your fingers.

2. Preheat the oven: Set your oven to 375°F (190°C) to get it ready for baking.

3. Sauté the onion and garlic: In a large pan over medium heat, heat the olive oil. Add the sliced red onion and minced garlic, cooking for about 7 minutes until the onion softens and begins to turn golden. Add the fresh corn and smoked paprika, sautéing for another 2 minutes to let the flavors meld together. Set this mixture aside.

4. Make the cornbread batter: In a large mixing bowl, combine the cornmeal, baking soda, granulated sugar, and sea salt. Create a well in the center of the dry ingredients and pour in the buttermilk and eggs. Mix until the batter is smooth. Finally, fold in the melted butter and the reserved onion and corn mixture until evenly combined.

5. Assemble the casserole: In a nonstick 9 x 13 x 3-inch baking pan (or lightly coat it with olive oil), place 6 of the Hatch chiles, smooth side down. Pour about 2 cups of the batter over the chiles and sprinkle with ¾ cup of grated cheddar cheese. Layer the remaining 6 chiles on top, also smooth side down. Pour the remaining batter (about 2½ cups) over the chiles and finish by sprinkling the last 1¼ cups of cheese on top.

6. Bake the casserole: Place the assembled casserole in the preheated oven and bake for approximately 25 minutes, or until the top is golden brown and the batter is set. For a deeper golden finish, you can place it under the broiler for an additional 30 seconds, keeping a close eye on it.

7. Cool and serve: Once baked, allow the casserole to cool in the pan for at least 20 minutes before slicing and serving. This will help the layers set nicely, making for easier servings.