1-First Step: Preheat your oven to 350°F (175°C) and line a 9×13-inch baking pan with parchment paper, leaving some overhang on the sides for easy removal later. This simple preparation ensures your bars will release cleanly after chilling.

2-Second Step: In a mixing bowl, combine 2 cups of all-purpose flour and 1/2 cup of granulated sugar. Add 1 cup of softened butter cut into cubes. Use your hands or a pastry cutter to work the butter into the flour mixture until it resembles coarse crumbs and holds together when squeezed. The secret to perfect shortbread is using room-temperature ingredients and not overworking the dough.

3-Third Step: Press the shortbread mixture evenly into the bottom of your prepared pan. Use the back of a measuring cup or glass to smooth the surface. For the best texture, prick the dough all over with a fork to allow steam to escape during baking. Bake for 20-22 minutes until the edges are lightly golden. While the shortbread bakes, you can begin preparing the caramel filling.

4-Fourth Step: In a medium saucepan, combine 14 oz of sweetened condensed milk, 1/2 cup of butter, and 1/2 cup of brown sugar. Cook over medium-low heat, stirring constantly to prevent burning. The mixture will bubble and thicken gradually. Continue cooking for 10-15 minutes until it reaches a rich amber color and thickens to a consistency similar to warm peanut butter. This traditional method creates the most authentic caramel flavor, though you can find healthy millionaire shortbread alternatives if you prefer a lighter version.

5-Fifth Step: Once the shortbread has cooled slightly but is still warm, carefully pour the hot caramel over the base. Use an offset spatula to spread it evenly. Allow this layer to cool completely at room temperature for about 30 minutes, or refrigerate for 15-20 minutes to speed up the process. A well-set caramel layer is essential for clean cutting later.

6-Sixth Step: While the caramel sets, prepare the chocolate layer. Place 12 oz of semi-sweet chocolate and 1/4 cup of butter in a heat-proof bowl. Microwave in 30-second intervals, stirring between each session, until about 90% melted. Then continue stirring until completely smooth. This gentle heating method prevents the chocolate from seizing and ensures a glossy finish.

7-Seventh Step: Pour the melted chocolate over the cooled caramel. Spread evenly with an offset spatula, working gently to avoid mixing the layers. For an elegant finish, you can create decorative patterns by dragging a fork across the surface while the chocolate is still slightly warm. Refrigerate the entire pan for at least 2 hours or until completely set.

8-Final Step: Use the parchment paper overhang to lift the bars from the pan. For clean cuts, wipe your knife with a damp cloth between slices. These millionaire shortbread bars are best served at room temperature to allow the caramel to soften slightly. Store in an airtight container at room temperature for up to 5 days or refrigerate for longer storage.