Chocolate Fudge Cake Doughnuts

Ingredients

• 2/3 cup Dutch-process cocoa
• 1 ¾ cups unbleached all-purpose flour
• 1 ¼ cups light brown sugar
• 3/4 teaspoon ground espresso or espresso powder
• 1 teaspoon baking powder
• 1 teaspoon baking soda
• 3/4 teaspoon salt
• 1 cup chocolate chips
• 2 large eggs
• 3/4 cup milk
• 2 teaspoons vanilla extract
• 2 teaspoons vinegar, white or cider
• 1/3 cup vegetable oil