Preheat oven to 325 degrees.
Grease an 8-inch square baking dish. Place chocolate, butter, sugar, salt and water in a small saucepan over very low flame.
Heat, stirring often, until the chocolate and butter are melted and the sugar is dissolved.
Pour into a mixing bowl. Stir in eggs, one at a time. Stir in the vanilla extract. Stir in the flour. Fold in nuts (optional).
Pour the batter into the prepared pan. Bake for 35 minutes. Cool completely before cutting. Dust with confectioners’ sugar if desired.
