Preheat oven to 350 degrees F. Line an 8 inch metal baking pan with non-stick foil.

Melt butter in a small saucepan set over medium heat. Add the chocolate, reduce heat to low or turn off the heat and stir until chocolate melts over residual heat. Cool slightly.

Whisk eggs in a mixing bowl, then whisk in salt, sugars and vanilla. Do this gently, so as not to whisk in to much air. Whisk in the chocolate. Fold in flour just until combined.

Pour batter into prepared pan. Sprinkle top with chopped nuts if desired.

Bake for 33-35 minutes or until shiny and beginning to crack on top.

Cool in pan on rack. Cut into brownie size of your choice.