In a large mixing bowl, whisk together the dry ingredients and the chocolate chips.
In a medium sized bowl, mash the bananas. Add the milk, vanilla, vinegar and butter. Whisk.
Add the wet mixture to the dry mixture and stir just until combined.
Scoop into greased or lined muffin cups. bake for 15 to 20 minutes. Watch carefully so the edges don't burn. cool in pan on a rack for 5 minutes or so, then remove from the pan and cool on a rack. Or eat them warm while the chocolate chips are still gooey!