1. Prepare the chiles: Begin by roasting and peeling the Hatch chiles. Once cooled, carefully slice them open to remove the stems and seeds, keeping the chiles intact for layering.

2. Preheat your oven: Set the oven to 375°F (190°C) to prepare for baking the casserole.

3. Sauté the onion and garlic: In a large skillet, heat the olive oil over medium heat. Add the sliced red onion and minced garlic, sautéing for about 7 minutes until the onion is soft and lightly browned. Stir in the corn and smoked paprika, cooking for an additional 2 minutes to blend the flavors. Remove from heat and set aside.

4. Mix the cornbread batter: In a large bowl, combine the cornmeal, baking soda, sugar, and sea salt. Create a well in the center, then pour in the buttermilk and crack in the eggs. Stir the mixture until smooth. Gently fold in the melted butter and the sautéed onion-corn mixture, ensuring everything is well combined.

5. Layer the casserole: In a nonstick 9 x 13-inch baking dish, arrange 6 of the Hatch chiles with the smooth side facing down. Pour about half of the cornbread batter (roughly 2 cups) over the chiles and sprinkle with 1 cup of grated cheddar cheese. Place the remaining 6 chiles on top, again with the smooth side down. Pour the rest of the batter over these chiles, followed by the remaining cup of cheddar cheese.

6. Bake the casserole: Bake the assembled casserole in the preheated oven for approximately 25 minutes, or until the top is golden brown and the batter has set. For an extra crispy top, you can broil it for an additional 30 seconds, watching closely to avoid burning.

7. Cool and serve: Allow the casserole to cool in the pan for at least 20 minutes before slicing into portions. Enjoy warm as a delightful side dish or main course!