These irresistible bars, with a shortbread base, melt-in-your-mouth like candy.
Heat oven to 325°F. Combine sugar and butter in large bowl. Beat at medium speed, scraping bowl often, until creamy. Add egg yolk; continue beating until well mixed. Reduce speed to low; add flour. Beat until well mixed.
Press evenly onto bottom of ungreased 15x10x1-inch jelly-roll pan.
Bake for 22 to 25 minutes or until lightly browned. (Bars will be soft.)
Sprinkle immediately with chocolate chips; let stand 3 minutes. Swirl chips slightly with table knife or back of spoon. Sprinkle with toffee bits.
Cool 1 hour; cut into bars with sharp knife while slightly warm.
*Substitute 1 (1.4-ounce) milk chocolate English toffee candy bar, crushed.
