Preheat the oven to
180º C. Line muffin moulds with paper cups.
Take flour, cocoa
powder, cinnamon powder, baking soda, baking powder and salt in a mixing bowl and mix well.
Take sugar, oil, egg
and vanilla extract in another mixing bowl and beat with an electric beater for 2-3 minutes or till thick and creamy.
Add the flour mixture
and beat at low speed till just incorporated. Add zucchini and chocolate chips and mix gently.
Put the batter into the
lined muffin cups, keep them in the preheated oven and bake for 30-35 minutes or till their tops spring back when lightly pressed.
Take the muffin tray
out of the oven and cool slightly, arrange them on a serving platter and serve warm.