Char chiles over gas flame or in broiler until blackened on all sides. Enclose in paper bag; let stand 10 minutes. Peel, seed and chop chiles. Set aside.
Preheat oven to 400°F Butter 9x5x2-inch metal loaf pan. Set aside.
In a medium bowl, whisk cornmeal, flour, sugar, baking powder, baking soda and salt to blend. Stir in cheese. Whisk buttermilk, eggs and butter in another medium bowl to blend. Add egg mixture to dry ingredients, and stir just until blended. Mix in chiles. Transfer batter to prepared pan.
Bake until deep golden brown on top and tester inserted into center comes out clean, about 45 minutes. (Check at about 20 minutes.).