Millionaire shortbread bars offer a polished, crowd-pleasing dessert with distinct layers and a satisfying finish. They are ideal for celebrations, sharing, or an everyday sweet treat.
Preheat your oven to 350F (175C). Line a 9x9 inch baking pan with parchment paper, leaving an overhang on two sides.
Beat the softened butter and granulated sugar together until smooth. Add the flour and salt, mixing until a crumbly dough forms. Press the dough firmly and evenly into the bottom of the prepared pan. Prick the surface all over with a fork.Bake for 20 to 22 minutes, until the edges are lightly golden. Let it cool while you prepare the caramel.
In a medium saucepan over medium heat, melt the butter with the brown sugar, stirring until dissolved. Pour in the sweetened condensed milk and stir constantly.Bring the mixture to a gentle boil, then reduce heat to medium-low and continue stirring for 6 to 8 minutes, until the caramel thickens and turns a rich golden amber color. Stir in the flaky sea salt.
Pour the hot caramel over the cooled shortbread base and spread it into an even layer. Let it cool to room temperature, about 30 minutes.
Melt the chocolate chips and coconut oil together in a microwave-safe bowl in 30-second intervals, stirring between each, until completely smooth. Pour the chocolate over the caramel layer and spread evenly.
Sprinkle a pinch of flaky sea salt over the chocolate while it is still wet. Refrigerate for at least 2 hours until everything is completely set and firm.
Lift the bars out using the parchment overhang. Use a sharp utensil dipped in hot water to make clean cuts into squares. Store in the fridge.