Salted Butter and Chocolate Chunk Shortbread Cookies

1. Prepare the Dough

In a large mixing bowl, beat the salted butter, granulated sugar, light brown sugar, and vanilla extract together on medium-high speed using an electric mixer until fluffy and well-combined, about 3 to 5 minutes. Reduce the mixer speed to low and add in the all-purpose flour, followed by the chopped dark chocolate, blending just until the dough is combined and the chocolate is evenly distributed.

2. Chill and Shape Dough

Divide the dough in half and shape each portion into a log about 2 to 2¼ inches in diameter. Wrap the logs tightly in plastic wrap and refrigerate until firm, about 2 hours.

3. Prepare for Baking

Preheat the oven to 350°F. Brush the logs with beaten egg, roll them in Demerara sugar, and slice into ½-inch-thick rounds. Place on a lined baking sheet and sprinkle with flaky sea salt.

4. Bake the Cookies

Bake the cookies for 12 to 15 minutes, until the edges are just beginning to brown. Allow the cookies to cool slightly on the baking sheet before serving.