Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13 inch baking pan.
In a large bowl, mix together the oil, margarine, sugar, eggs and 1 teaspoons vanilla until well blended. Combine the flour, 4 tbsp.cocoa, baking powder, cinnamon, baking soda and salt; stir into the sugar mixture. Fold in the zucchini and mini chocolate chips. Spread evenly into the prepared pan.
Bake for 40 to 45 minutes in the preheated oven, until brownies spring back when gently touched. To frost, pour bag of milk chocolate chips over warm brownies and spread.