Preheat oven to 425°F (220°C). Lightly oil or spray a 12-cup muffin pan and place in oven while preheating.
In a medium bowl, whisk together flour, cornmeal and baking powder. In a smaller bowl, lightly whisk together egg, sour cream and milk. Pour liquid mixture over dry mixture; stir with a wooden spoon just until dry ingredients are moistened. Add butter, corn, jalapeño and 1/2 cup (125 mL) of the cheese. Stir lightly but evenly.
Carefully remove pan from oven. Spoon batter into cups; sprinkle with remaining cheese. Bake 20 min. or until a toothpick inserted in centre comes out clean. Let cool in pan on wire rack for 5 min. Remove muffins from pan to cool ompletely.
These muffins freeze well. Just thaw overnight in the fridge or microwave on defrost setting for fresh-tasting cornbread the next day.