Pre-heat the oven to 180 °C (350 °F). Grease a 28 x 20 cm (11 x 8 inch) baking pan.
Mix the flour, oat bran, cocoa, flax seed, and baking powder together in a bowl.
In a large bowl, beat the oil and sugar together. Add the eggs, applesauce, and the vanilla. Mix well. Fold in the dry ingredients. Add the grated zucchini and the chocolate chips. Mix well. The batter will be thick.
Pour the batter into the baking pan and smooth the surface with a spatula. Bake in the centre of the oven for 30 minutes. Cool before cutting into 16 pieces.
Storage: These brownies will store well in a sealed container in the refrigerator for a week, or for six months in the freezer.
Health Information: Using applesauce significantly reduces the fat and sugar content in recipes.