Preheat oven @180° C for 10 minutes. Line the muffin tray with liners. If you dont have liners just grease the tray with butter or oil.
In a mixing bowl place the sift and add in the flour, baking powder, baking soda, coffee powder and salt. Sieve them together.
To the dry ingredients mixture add in the brown sugar, vanilla essence, oil, milk, mash banana and vinegar.
Fold the mixture together and make a batter.
Take the chocolate chips and coat it in little flour. This will prevent the chocolate chips from sinking at the bottom.
Add in the chocolate chips into the batter and give a quick gentle mix. Do not over mix them.
Scoop the batter into the lined muffin tray till ¾th of the cavity.
Tap the muffin tray for 2-3 times to level it and release any air bubbles inside.
Sprinkle some chocolate chips over the muffins.
Bake at a preheated oven @180° C for 20 minutes. A toothpick or skewer inserted should come out clean. (I bake with both the filaments on).
Baking time will differ depending upon your oven temperature settings because each oven reacts differently.
Remove from the oven and transfer onto a cooling rack and allow to cool down completely before serving.