1-Preheat the oven: Preheat oven to 400°F with rack in middle; grease an 8-inch square baking pan.

2-Whisk dry ingredients: Combine flour, cornmeal, sugar, baking powder, baking soda, and salt, breaking up any cornmeal lumps.

3-Whisk wet ingredients: Beat egg, then whisk in milk, melted butter, and sour cream until smooth.

4-Combine wet and dry: Pour wet into dry and fold with spatula just until no dry pockets remain; avoid overmixing.

5-Fold in add-ins: Gently stir in drained green chiles and shredded cheddar, leaving a few streaks.

6-Transfer to pan: Scrape batter into prepared pan, spread evenly, and dot top with cold butter pieces.

7-Bake: Bake 25–30 minutes until deep golden and toothpick comes out clean or with moist crumbs (check at 22 min for dark pan).

8-Cool: Cool in pan on wire rack at least 20 minutes before slicing to prevent crumbling.