These bars are super fast to whip up, and hard to resist!
I double this recipe, and put it on a large cookie sheet
1/2 cup butter, softened
3/4 cup packed brown sugar
1 egg
1/2 teaspoon vanilla
1 cup all-purpose flour
1/8 teaspoon salt
3/4 cup semisweet or milk chocolate chips
1/3 cup chopped walnuts or pecans opt.
1/3 cup chocolate-covered toffee pieces  

Preheat oven to 375 degrees F. In a large mixing bowl beat butter with an electric mixer on medium to high speed for 30 seconds. Add the brown sugar, egg, and vanilla. Beat until combined, scraping sides of bowl. Beat in flour and salt until combined.
Spread dough evenly in an ungreased 13x9x2-inch baking pan. Bake for about 15 minutes or until edges begin to brown and surface is dry. Remove from oven and immediately sprinkle with chocolate pieces. Let stand about 2 minutes or until chocolate is softened; spread evenly. Sprinkle with nuts and toffee pieces. Let cool in pan on wire rack 30 minutes. Cut into bars.
Makes 36 bars