Use the paddle attachment to cream the butter and two sugars until light, fluffy and creamy.
1 cup Butter, ½ cup Granulated, ¼ cup Brown sugar
Add the vanilla extract and mix well.
1 tablespoon Vanilla extract
Sift the flour, cinnamon, and salt and add to the butter sugar mixture in two passes. mix until there is no trace of dry flour. Do not overmix.
1 teaspoon Cinnamon, ¼ teaspoon Salt, 2½ cups All-purpose flour
Roughly chop the chocolate bar and add to the above mixture. Use a spatula to mix the chocolate in.
7 ounce Semi-sweet Chocolate
Place a piece of cling wrap or wax paper on the counter and dump the dough on it. Divide the dough into two equal parts.
Roll each portion of the dough into a log shape and wrap the cling wrap or wax paper around the dough tightly. Tighten both ends like a candy wrapper. Place the logs on a small tray or plate and put them in the fridge for one hour.
In the meantime preheat the oven to 350℉ and line two baking sheet with parchment paper and set aside.
After the dough is hard enough, place one log on the counter. Work on one log at a time, and keep the second one in the fridge. Use a serrated knife and cut each log into discs with ½ inch thickness.
Roll the sides of the Chocolate Shortbread Cookies into turbinado sugar and place them on the lined baking sheets. Leave a one-inch space between them. These cookies don't expand too much.
½ cup Turbinado sugar
When cutting the log, you might experience dough cracks and breaks, and that is totally normal. Use your fingertips to press the dough together and cover the crack!
Bake them for 12-14 minutes or until the edges start to get golden. Leave them on the baking sheet for 10 minutes, and then transfer to the cooling rack to cool down completely.