Melt the chocolate and butter in a large, heavy saucepan over low heat, stirring occasionally.

Remove the pan from the heat and add the salt, vanilla, and sugar. Mix well.

Add eggs, one at a time, mixing after each one. Add the flour and beat until smooth. Stir in the walnut pieces.

Pour half of the batter into a greased 9x13-inch baking pan and use the back of a spoon or spatula to smooth the surface.

Freeze the batter for 30 minutes.

Preheat the oven to 350 degrees F.

When the batter is frozen, spread the preserves on top of the batter in a thin layer. Pour the remaining batter over the preserves and gently smooth it over to cover the preserves.

Bake for 40-45 minutes, or until a toothpick comes out clean. You want the brownies moist and fudgy, so be careful not to overbake!

Cool the pan on a wire rack for 10 minutes before slicing.