Chocolate chunk salted shortbread

Instructions

1. Using a stand mixer fitted with the paddle attachment, beat the butter, caster sugar, light brown sugar and vanilla paste on medium-high speed for 3–5 minutes or until light and fluffy. Using a spatula, scrape down the sides of the bowl. Reduce the speed to low, then slowly add the flour, followed by the chocolate chunks and beat until just combined.
2. Divide the dough in half, placing each half on a large piece of plastic wrap. Fold the plastic over so that it covers the dough to protect your hands from getting sticky. Using your hands, form the dough into a log shape; rolling it on the counter will help you smooth it out (you can also do this using baking paper). Each half should form two logs about 5-7 cm in diameter. Refrigerate for 2 hours or until totally firm.
3. Preheat the oven to 175°C. Line two baking trays with baking paper. Place the demerara sugar on a tray.
4. Unwrap the logs, then brush all over with the beaten egg. Roll the logs in the demerara sugar, then slice each log into 1.5 cm-thick rounds. Place them on the prepared baking trays about 2 cm apart and sprinkle with a little flaked salt. Bake for 12–15 minutes or until the edges are just beginning to brown. Remove from the oven and stand on the trays for 15 minutes to cool slightly.