In large mixer bowl, cream butter and sugar. Gradually add eggs, one at a time.

Add vanilla and chocolate. Sift in flour, baking powder and salt. Add walnuts and mix slowly until smooth.

Pour half of batter into lined and greased 10- x 16-inch baking pan.

Blend or process all filling ingredients until smooth. Pour over cake batter. Scoop remaining cake batter over cheese. Smooth batter with wet spatula.

Bake for one hour at 350 degrees Fahrenheit.

Cut into two-inch squares or one-and-a-half-inch bars.