- Preheat oven to 180°C (350°F). Place the rack in the upper part of the oven.
- Use electric beaters (stand or hand-held) to whisk egg whites until frothy. Add the milk, oil, and vanilla.
- Combine the flour, flax seed, baking powder, powdered milk, cocoa, and sugar in a large bowl.
- Add wet ingredients to dry ingredients and combine with a fork.
- Pour mixture into a round, 20-cm (8-in.) baking pan.
- Bake 12 to 15 minutes, until centre is almost completely baked, but still tender.
- Let sit 5 minutes before removing from pan. Set aside to cool.
- Cut into 10 triangle-shaped slices and insert a stick in each one to act as the tree trunk.
- Mix together all icing ingredients and transfer to a sealable plastic bag (like a sandwich bag). Cut off one corner to create a makeshift pastry bag. Decorate each tree with mint icing.
When they come out of the oven, the brownies won't seem quite done. Nevertheless, they continue baking after you remove them from the oven. This will produce spongier brownies. These brownies contain half the fat and three times the fibre of their store-bought counterparts. A guilt-free treat to savour!