* 3/4 cup milk 
  * 2 tablespoons white vinegar 
  * 1 cup all-purpose flour 
  * 2 tablespoons white sugar 
  * 1 teaspoon baking powder 
  * 1/2 teaspoon baking soda 
  * 1/2 teaspoon salt 
  * 1 egg 
  * 2 tablespoons butter, melted cooking spray