Start by preheating the oven at 170º.
Wash the zucchinis well and grate them.
Place the grated zucchinis in a cloth and squeeze well until the excess water is removed. Set aside.
In a big bowl mix the greek plain yogurt, brown sugar, and coconut oil and mix well with a wires whisp.
Add the eggs and vanilla essence and mix well.
Add the zucchini and fold it gently.
In another bowl, mix the dried ingredients: flour, cocoa, baking powder, baking soda, and salt.
Add the mixture of liquid ingredients mixture and incorporate well.
Now that the batter is ready, add ⅔ of the chocolate pieces or chips and lightly fold them into the mixture.
Place the batter in a previously greased baking pan and place the remaining chocolate chips or nuggets on top.
Bake for 45 min or until cooked inside.