Preheat oven to 350 degrees.
Mash the bananas and grate the zucchini, and set aside.
In a medium bowl, add the flour, sugar, soda, baking powder, salt and cinnamon, and stir.
Add the butter, milk, eggs, extract, bananas and zucchini, and mix well.
The batter may still have some lumps, but don't over mix.
Stir in the chocolate chips, and spoon batter into a greased muffin pan. I filled all 12 cups to the brim, and this produced some nice monster muffins.
Add extra chips to the tops of the muffins, if you like, and bake for about 25 minutes, or until tops are firm and a toothpick comes out clean from the center of the muffins.