Portion: 24 cookies
2 cups all purpose flour, plus more for rolling
1/2 tsp salt
1 cup unsalted butter (2 sticks), room temperature
1/2 cup sugar
1 tsp vanilla extract
3 oz bittersweet chocolate, finely chopped
1 tsp vegetable oil
In the bowl of an electric mixer fitted with the paddle attachment, cream on medium speed butter, sugar and vanilla until fluffy, 3 to 5 minutes. Add sugar, continue to beat until very light in color and fluffy, about 2 more minutes. Sift flour and salt into mixture, combine on low, scraping sides of bowl with a spatula if necessary, until flour is just incorporated and dough sticks together when squeezed with fingers.
Place a piece of parchment paper on a clean surface, dust with flour. Roll dough to 1/4 inch thinkness, and move dough to a cookie sheet. Chill in freezer until firm, about 30 minutes.
Preheat oven to 325F.
Using the back of a knife, cut dough lengthwise into 1-inch wide strips, then cut crosswise into 3-inch bars.
Bake until firm and barely starting to color, 15 to 20 minutes, rotating halfway through. Cool completely on wire rack.
In a heat proof bowl, microwave chocolate on high for 1 minutes. Stir chocolate until completely melted. Stir in the oil. Dip one end of each cookie into the chocolate mixture. Place cookies on a piece of parchment paper and allow chocolate to dry. Serve, or store in an airtight container for up to 3 weeks.
Remember to rest the butter until room temperature before starting, or you'll be unable to combine the butter and sugar. It usually takes 2 to 3 hours. If you do not have enough time, grate the hard butter with a grater, and the butter will soften in less time.
Chilling the dough before baking will make the cookie more light.