Preheat oven to 350 degrees F (175 degrees C). Grease and flour an 8x8 inch pan.
In a small saucepan over medium heat, melt margarine and cocoa together, stirring occasionally until smooth. Remove from heat and set aside to cool. In a large bowl, beat eggs until frothy. Stir in the sucrolose sweetener. Combine the flour and salt; stir into the egg mixture then mix in the cocoa and margarine. Finally stir in the 1/4 cup of milk and if desired, the walnuts. Pour into the prepared pan.
Bake for 25 to 30 minutes in the preheated oven, until a toothpick inserted into the center, comes out clean. To make frosting, Mix together the sugar free chocolate pudding mix and 1 cup skim milk using an electric mixer. Mix for about two minutes or until thick. Spread over cooled brownies before cutting into squares.