Instructions

1. Preheat your oven to 350°F (175°C). Line an 8x8 inch baking pan with parchment paper, allowing some overhang on the sides for easy removal later. This will help prevent the shortbread from sticking to the pan.
2. In a large mixing bowl, cream together the softened unsalted butter and powdered sugar using an electric mixer on medium speed. Beat until the mixture is light and fluffy, which should take about 3-4 minutes.
3. Add the vanilla extract to the butter and sugar mixture, mixing until well combined.
4. In a separate bowl, whisk together the all-purpose flour and salt. Gradually add this dry mixture to the butter mixture, mixing on low speed until just combined. Be careful not to overmix; the dough should come together but still be crumbly.
5. Fold in the melted dark chocolate and orange zest using a spatula or wooden spoon. Ensure that the chocolate and zest are evenly distributed throughout the dough.
6. Transfer the dough into the prepared baking pan, pressing it down evenly with your fingers or the back of a spatula to form a smooth layer.
7. Bake in the preheated oven for 20-25 minutes, or until the edges are lightly golden and a toothpick inserted in the center comes out clean. Keep an eye on it towards the end of the baking time to prevent over-baking.
8. Once baked, remove the pan from the oven and let it cool in the pan for about 10 minutes. Then, use the parchment overhang to lift the bars out of the pan and transfer them to a wire rack to cool completely.
9. Once cooled, cut into 16 equal bars. You can dust the bars with additional powdered sugar for an elegant touch, if desired.
10. Store the Dark Chocolate Orange Shortbread Bars in an airtight container at room temperature for up to a week, or refrigerate for longer freshness.