8 1-ounce squares semisweet chocolate

6 tablespoons butter

4 eggs

1 ½ cups sugar

1 cup flour

½ teaspoon slat

1 teaspoon baking powder

2 teaspoons vanilla extract

1 cup walnuts, chopped

For the plain Batter

4 tablespoons butter, at room temperature

6 ounces cream cheese

½ cup sugar

2 eggs

2 tablespoons flour

1 teaspoon vanilla extract

Preheat the oven to 350oF.  Line the bottom and sides of a 13- X 9- inch pan with wax paper and grease.

Melt the chocolate and butter over very low heat, stirring constantly.  Set aside to cool.  Meanwhile, beat the eggs until light and fluffy.  Gradually add the sugar and continue beating until blended.  Sift over the flour, salt, and baking powder and fold to combine. 

Stir in the cooled chocolate mixture.  Add the vanilla and walnuts.  Measure and set aside 2 cups of the chocolate batter.

For the plain batter, cream the butter and cream cheese with an electric mixer.  Add the sugar and continue beating until blended.  Beat in the eggs, flour, and vanilla.   Spread the unmeasured chocolate batter in pan.  Pour over the cream cheese mixture.  Drop spoonfuls of the reserved chocolate batter on top.

With a metal spatula, swirl the mixtures to marble.  Do not blend completely.  Bake until just set, 35-40 minutes.  Unmold when cool and cut into squares for serving.