Nigella's Chocolate Chip Muffins

Bahan-bahan (20 porsi)

• 1¾ cups all-purpose flour
• 2 teaspoons baking powder
• ½ teaspoon baking soda
• 2 tablespoons cocoa powder
• ¾ cup superfine sugar
• ¾ cup Hershey chocolate chips (plus 1/4 cup (40 g) for sprinkling)
• 1 cup milk
• ⅓ cup vegetable oil (plus 2 teaspoons )
• 1 egg
• 1 teaspoon pure vanilla extract