Toffee Squares

Preheat the oven to 350F. Line a 9-by-13-inch baking pan with parchment.

Prepare the crust. In a large bowl, with an electric mixer, beat together the butter and sugar on medium speed until light, about 2 minutes. Beat in the egg yolk, vanilla, and salt. On low speed, gradually beat in the flour just until mixed. The dough will be stiff. Pat the dough evenly over the bottom of the baking pan.

Bake in the center of the oven until pale gold on top, about 20 minutes.

Remove the pan from the oven and scatter the chocolate pieces evenly over the crust. Return the pan to the oven for 1 minute. Remove the pan again and, using a knife, spread the chocolate evenly over the crust. Sprinkle evenly with the almonds if desired.

Let cool completely in the pan on a wire rack. Then gently lift the parchment so that the bars can be placed on a flat cutting surface. Using a sharp knife, cut into small squares.