Preheat the oven to 375 degrees.
Line a muffin tin with paper liners.
In a medium bowl, add the cocoa, flour, baking soda, baking powder, cream of tartar and salt and whisk to combine. Set aside.
In a large mixing bowl, beat the shortening and sugar until smooth and then beat in the eggs and vanilla. Slowly add a little of the flour, mix, a little of the banana, mix, and continue to alternate between the two. Fold in the chocolate chips. Fill each muffin tin 2/3 full.
Bake for 10-13 minutes.