Preheat oven to 350. Butter an 8 inch square baking pan, Mix flour and salt in medium bowl. Melt semisweet chocolate with the butter in a double boiler over barely simmering water. Transfer chocolate mixture to medium bowl and let cool for 5 minutes. Stir in white and milk chocolate chips and half the pecans. Add eggs, beating until just blended. Stir in the mixed dry ingredients. Spoon batter into prepared pan in an even layer. Sprinkle with remaining pecans. Bake until firm to the touch, 35 to 40 minutes. Let cool completely before cutting into bars.
The Golden Book of Chocolate