Preheat oven to 350 degrees F (175 degrees C). Coat muffin pans with non-stick spray, or use paper liners.
Sift together the flour, baking powder, baking soda, cinnamon, nutmeg and salt; set aside.
Blend oil and sugar in a large bowl until smooth. Add egg and vanilla and blend well. Repeat with bananas.
Fold into flour mixture with milk and mix until smooth. Add raisins and/or coconut at this phase. Scoop into muffin pans and, if using, top with chocolate chips.
Bake in preheated oven. Bake mini muffins for 12 to 15 minutes, and large muffins for 23-25 minutes. Muffins will spring back when lightly tapped.