Preheat oven to 450º. Combine 1 cup low-fat buttermilk, 1/4 cup canola oil, 3 tablespoons sugar, 1/2 teaspoon salt, and 2 large eggs in a large bowl, stirring with a whisk. Sprinkle 4 teaspoons baking powder over batter; whisk until blended. Fold in 1 cup yellow cornmeal, 4.5 ounces (about 1 cup) all-purpose flour, and 1 chopped jalapeño pepper (do not remove seeds). Spoon batter into a 10-inch cast-iron skillet coated with cooking spray. Bake at 450º for 20 minutes or until lightly browned.