Preheat the oven to 350F degrees and line two muffin tins with muffin papers. You'll end up with about 14-16 cupcakes total.
In a large bowl whisk together the flour, baking soda, cinnamon and salt. Set aside.
In a separate large bowl using a hand held or stand mixer on medium speed, beat together the butter and sugars until fluffy (about 2-3 minutes). Add in the vanilla and eggs and continue beating. Turn off the mixer and stir in the bananas. With the mixer on low speed carefully add in the flour mixture until almost combined, followed by the milk. Once smooth and no lumps remain, turn off the mixer and stir in the chocolate chips using a wooden spoon or rubber spatula.
Spoon the cupcake batter into the prepared muffin tins, filling each cavity about ⅔ to ¾ full. Bake in the preheated oven for 15-18 minutes or until an inserted toothpick comes out clean (apart from any melted chocolate chips).
Allow to cool in the muffin tin for 10 minutes before removing and cooling on a wire rack.
To make the buttercream, in a large bowl whisk together the cocoa powder and icing sugar. In a separate large bowl using a stand or hand held electric mixer - beat the butter until light and fluffy and no lumps remain. Add in vanilla and salt. With the mixer on medium speed, add in the cocoa and icing sugar about ½ cup at a time. Turn the mixer to high and beat in the whipped cream until fluffy. Add in a little extra icing sugar or whipped cream as needed to get the desired consistency.
Frost the cupcakes either using a piping bag or a flat edge knife. I used a 1M tip with a piping bag to frost mine. Optionally, decorate with mini chocolate chips and dried banana chips