Preheat oven to 350 F (176 C). Melt the butter and cream it together with the sugar in a large bowl. Use a mixer or wooden spoon.
Next add in the egg, vanilla extract, and sour cream and mix that in until just combined.
Peel and mash up the ripe bananas. Use or fork, rolling pin, or meat tenderizer. Add the bananas to the batter and mix until just combined. Put the mixer away now if you are using one. We don't want to over mix the batter.
Sift the flour, salt, baking soda, baking powder, and cocoa powder into the bowl. Or place them in a separate bowl and whisk them together, then add to the main bowl. Stir those ingredients in with a wooden spoon or strong spatula until just combined.
Add all but about 1/4 cup of the chocolate chips and stir them in. Use whatever flavor of chocolate chips you want. To make these a little more healthy use sugar-free chocolate chips.
Place 12 paper cups in the muffin pan and fill them up with batter. Then top them off with the remaining chocolate chips. In to the oven they go.
Bake them for 15 to 20 minutes until a toothpick comes out clean after being poked. Let the muffins cool before serving. Enjoy!