1. heat oven to 325 degrees F. Line a 13X9 1/2" pan with double layer of aluminium foil. Butter the bottom of foil.

2. Stir flour, soda, baking powder and salt together. Put semi sweet chocolate in separate large bowl.

3. In a medium saucepan combine butter, sugar, corn syrup and water. Cook until butter melts, sugar is dissolved and mixture comes to a boil. Pour the hot syrup over the chocolte and let it stand for a minute or two to melt chocolate. Whisk until smooth.

4. One at a time, whisk in the eggs, blending until smooth. Whist in vanilla and flour mixture, until batter is smooth. Fold in 1 cups of the walnuts and 6 oz of the Swiss chocolate.

5. Spread batter into pan. Top with remaining walnuts and chocolate.

6. Bake for 4-50 minutes, until toothpick comes out with a few moist crumbs. Cool, cover with plastic, and let sit 6 hrs. At least.