Preheat your oven to 350ºF. Grease a 9 x 9 x 2 inch baking pan with margarine. Melt the margarine and chocolate in a large saucepan over very low heat. Remove the saucepan from the heat. Stir in the sugar, flour, baking powder, vanilla and eggs and beat well with an eggbeater. Stir in the nuts. Pour the batter into the baking pan. Bake for 30 minutes. Remove the pan from the oven and place it on a rack. Once the brownies are cool, cut them into squares. Makes 16 brownies