Preheat the oven to 350F. Combine the flour, 1 cup sugar and 1/2 cup softened butter in the medium bowl of an electric mixer. On low speed, beat the mixture until mixed. On medium speed, beat the mixture until smooth, 3 to 4 minutes. Pat the mixture evenly over the bottom of an ungreased 9 X 13 X 2 inch baking dish. Spread the pecans evenly over this mixture. Combine the 2/3 cup butter with the remaining 1/2 cup sugar in a medium saucepan. Heat to boiling, stirring constantly, over medium heat. Boil 1 minute. Spread evenly over crust in pan. Bake until golden and bubbly, about 18 minutes. Remove the bars from the oven and immediately sprinkle the chocolate bits over the top. Allow to melt slightly and then, using the sharp point of a knife, cut through the chocolate, making swirls. Do not spread the chocolate. Cool completely on a wire rack before cutting into bars. Makes: About 36 Brownies