1 3/4 cups all-purpose flour
2 teaspoons baking powder
1/2 teaspoon baking soda
3 tablespoons best quality cocoa powder
3/4 cup superfine sugar
3/4 cup semisweet chocolate chips, plus 1/4 cup for sprinkling
1/2 cup milk
1/2 cup sour cream
1/3 cup plus 2 teaspoons vegetable oil
1 egg
1 teaspoon pure vanilla extract

Preheat the oven to 400 degrees F.

Put the flour, baking powder, baking soda, cocoa, sugar, and 3/4 cup of the chocolate 
chips into a large bowl. Pour all the liquid ingredients into a measuring jug. 
Mix the dry and wet ingredients together, remembering that a lumpy batter makes the 
best muffins. Spoon into the prepared muffin cases. Sprinkle the remaining 1/4 cup 
chocolate chips on top and then bake for 20 minutes or until the muffins are dark, 
risen and springy.