Preheat oven to 350-degrees. Line a muffin tin with cupcake liners and spray with oil.
In a medium bowl, whisk together flour, baking soda, baking powder, cream of tartar, and salt.
In the bowl of the mixer, add vegetable oil and sugar. Mix well. Add egg, mix again. Add the zucchini and mix to combine. Slowly add dry ingredients to bowl, alternate by adding a bit of mashed banana.
Fold in the chocolate chips. Using an ice cream scoop, fill muffin cups about ⅔ full. Bake for 15-18 minutes.
Recipe by the minimalist table at https://www.daraboxer.com/theminimalisttable/chocolate-chip-zucchini-banana-muffins/