1. Pre-heat the oven to 180oC.
2. Mix the ground flax seed and water together and leave to one side.
3. Melt the margarine in a small pan. Once melted, add the chocolate and stir until melted completely.
4. Add the sugar, milk, vanilla and flax mix to the pan and stir until completely combined.
5. Measure out the flour, cocoa, salt and baking powder into a large bowl.
6. Slowly add the wet mix to the dry whilst stirring constantly.
7. Chop up the walnuts into smaller chunks and add to the brownie mix.
8. Line a brownie tray (around the size of a 20cm cake tin) with greaseproof paper, foil or margarine to stop the brownie from sticking to the bottom.
9. Cook the brownies for 25 minutes and then leave them to cool completely on the side before removing from the tin and cutting. Please note that if you do not leave them to cool, they will be very difficult to cut, but still just as delicious!