Heat oven to 325℉/163℃.
Line a cupcake pan with cupcake papers, or spray with baking spray. Set aside.
In a medium bowl, whisk together flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
With an electric mixer, beat shortening and sugar until light and fluffy, 2-3 minutes.
Add eggs and yolk, one at a time, beating well after each addition.
Beat in vanilla.
Add flour mixture alternately with milk, beginning and ending with flour mixture.
Fill muffin cups ¾ full.
Bake for 18-20 minutes, or until done.