Millionaire's Shortbread
Author: 
Yield: 24 bars
 
Ingredients
For the shortbread
  • ½ cup sugar
  • 1¼ cups (2½ sticks) unsalted butter, softened
  • 2½ cups all-purpose flour
  • 1 large egg yolk, slightly beaten
For the caramel filling
  • 28 ounces sweetened condensed milk (two 14-ounce cans)
For the chocolate glaze
  • 6 ounces dark chocolate (60% cacao), coarsely chopped
  • 1 teaspoon light corn syrup
  • ½ cup (1 stick) unsalted butter, softened, cut into cubes
Instructions
Make the shortbread
  1. Preheat the oven to 350 degrees F. Butter the bottom and sides of a 9-by-13-inch baking pan.
  2. In the bowl of an electric mixer fitted with the paddle attachment, beat the sugar and butter together until blended.
  3. Add 2 cups of the flour and beat until well combined. Add the egg yolk and beat for a few seconds, or until just combined.
  4. Turn the dough out onto a lightly floured work surface. Dust the top of the dough and your hands with a little flour. Use your hands to gently work the dough into a 6-by-6-inch square. You will have to turn the dough and sprinkle the top with flour as you go. Sprinkle the remaining ½ cup flour on the surface of the dough. Fold the dough over and knead until incorporated, then flatten the dough into a rectangle. Transfer the rectangle to the prepared pan and press it into the pan.
  5. Prick the dough all over with a fork and bake in the center of the oven for 20 to 22 minutes, until golden brown. Transfer to a wire rack and let cool completely.
Make the caramel filling
  1. Stovetop method: Put the sweetened condensed milk in a medium heatproof bowl and set it over a saucepan of boiling water over low heat. Cook for 1 to 1 ½ hours, until thick and caramel colored. Remove the bowl from the pan and beat until smooth.
  2. Microwave oven method: Put the sweetened condensed milk in a large microwave-safe bowl. Cook on 50 percent power (medium) for 4 minutes, stirring briskly halfway through, until smooth. Cook on 30 percent power (medium-low) for 12 to 18 minutes, until very thick and caramel colored, stirring briskly every 2 minutes, until smooth.
  3. Pour the caramel filling over the cooled shortbread and place the pan in the refrigerator until cool, about two hours.
Make the chocolate glaze
  1. In a large nonreactive metal bowl, combine the chocolate, corn syrup, and butter. Set the bowl over a saucepan of simmering water and cook, stirring with a rubber spatula, until the mixture is completely smooth. Remove the bowl from the pan and stir for 30 seconds to cool slightly. Pour the mixture over the chilled caramel layer and use an offset spatula to spread it into an even layer.
  2. Put in the refrigerator for 1 hour, or until the glaze hardens.
  3. Remove the pan from the refrigerator 30 minutes before serving so as not to crack the chocolate glaze. Cut into squares and serve.
  4. The bars can be stored in the refrigerator, tightly covered, for up to 4 days.
Recipe by Baked Sunday Mornings at http://bakedsundaymornings.com/2019/01/18/in-the-oven-millionaires-shortbread/