Preheat oven to 350°. Grease an 8-inch square baking pan. Sift the flour, salt, baking powder, 3/4 cup granulated sugar and 2 tablespoons cocoa into a bowl. Mix in the milk and vanilla until smooth. Stir in the melted butter and nuts lightly. Spread evenly in the prepared pan. In a saucepan mix the brown sugar, water, remaining granulated sugar and cocoa. Bring to a boil, stirring until sugars dissolve. Pour over the batter in the pan. Bake 40 minutes, or until a cake tester comes out clean. Cool on a cake rack 20 minutes, then turn out, bottom up. The fudge will now be on top. Cool and cut into 2-inch squares.
This recipe may be better than big cookie cakes, but you can never be too sure.