Rich and decadent, these Millionaire Shortbread bars feature layers of shortbread cookie, gooey caramel, and thick chocolate ganache for the ultimate dessert.
Make the Crust: Preheat oven to 350 degrees F. Line a 9-inch square pan with aluminum foil, allowing at least an inch overhang on all sides. Spray with nonstick cooking spray).
In a large bowl, whisk together the flour, brown sugar, cornstarch and salt, making sure there are no lumps of brown sugar remaining. Add the butter and cut into the flour mixture using a pastry blender or two knives until a coarse meal forms. Add the ice water and egg yolk and blend with a fork until moist clumps form. Dump the dough into the prepared pan and press into an even layer. Bake until golden brown, about 20 minutes.
Make the Caramel: Whisk the sweetened condensed milk, brown sugar, butter, golden syrup and salt together in a medium saucepan over medium heat until the sugar dissolves, the butter melts and the mixture comes to a boil. Attach a candy thermometer to the side of the pan and boil, whisking constantly, until the caramel is thick and the temperature registers 225 degrees F, about 6 minutes. Quickly whisk in the vanilla extract and pour the caramel over the prepared crust; cool for about 15 minutes, or until the caramel is set.
For Chocolate Ganache: Place the chocolate and cream in a microwave-safe bowl and microwave in 30 second intervals on 50% power, stirring between each, until the chocolate is melted and smooth. Spread the chocolate over the caramel layer. Refrigerate the bars until the chocolate is set, at least 1 hour.
Lift the bars out of the pan and transfer to a cutting board. Cut into squares and serve. Leftovers should be stored in an airtight container in the refrigerator for up to 5 days.
Notes
Storing: Keep millionaire shortbread bars stores in an airtight container in the refrigerator for up to 5 days.
Freezing: For longer storage, I suggest freezing. Store the bars pre-sliced in a freezer-safe, air-tight container for up to 3 months.
Shelf-Life: These delicious shortbread cookie bars will keep for up to 5 days in the refrigerator or up to 3 months in the freezer.