In a large bowl, sift flour, baking powder, baking cocoa, cinnamon, salt, and baking soda. Combine sugar, coffee, buttermilk, grapeseed oil, vanilla, eggs, and egg yolks in another large bowl. Beat until the egg mixture is blended. Add dry ingredients and beat on medium speed until well blended, about 4 minutes. Stir in chocolate chips.
Heat oven to 325°F/165°C. Spoon batter into cupcake papers, filling about 2/3 full. Bake until the center of the cupcake is firm to the touch; about 26-28 minutes. Makes 3-4 dozen cupcakes or about 90 mini cupcakes (bake 20-22 minutes). If desired, frost with a simple vanilla butter cream frosting with chocolate swirl topping.
*Dusting chocolate chips lightly with flour, helps the chocolate chips from going to the bottom of the bowl.