Preheat the oven to 220C / 425F
Prepare you muffin pan with 12 parchment muffin liners
In a large bowl mix together the flour, sifted cocoa powder, baking powder & soda (or levure chimique in France,) salt and cinnamon until it is homogenous.
In another bowl blend together oil, sugar, eggs, vanilla, yogurt and zucchini.
Mix the wet ingredients into the dry ingredients. Don't overdo it, but make sure there are no dry bits left.
Fill the muffin liners to the top and sprinkle with chocolate chips.
Place in the oven for 5 minutes at 220/425 and after without opening the oven door reduce the heat to 175C/350F for 15 more minutes until a toothpick comes out clean