Chocolate Shortbread Buttons

From The City Cook.  Big City, Small Kitchen. Limitless Ingredients, No Time.  Published by Simon & Schuster. © 2010.

• Servings: Makes about 15 cookies.

I love these cookies because while intensely chocolate, they aren't too sweet. And I call them buttons because I make them round and small, about 1 1/2 to 2 inches in diameter, and using the prongs of a fork, I add two little marks on each cookie's surface like the thread holes on a button. Even if you don't bake, these are really easy to make.

Ingredients

• 4 tablespoons (1/2 stick) unsalted butter, at room temperature
• 2 1/2 tablespoons sugar, plus more for rolling out the dough
• 1/2 teaspoon vanilla extract (not vanilla flavoring)
• 1/2 cup all-purpose flour
• 2 1/2 tablespoons unsweetened cocoa (either natural or Dutch-processed is fine)
• Pinch of fine salt

Directions

1. Preheat the oven to 275° F. Line a cookie sheet with parchment paper or a silicone liner.
2. Using an electric mixer, cream the butter in a mixing bowl until fluffy, about 2 minutes. Add the sugar and vanilla extract and beat until well blended, about 2 minutes.
3. Sift together the flour, cocoa and salt. Add to the butter mixture and mix at medium speed until completely combined and smooth. Using a spatula, transfer the thick, mixed dough to a piece of plastic wrap and refrigerate for about 15 minutes to let the dough rest.
4. Sprinkle sugar lightly on a clean counter or cutting board, add the dough, and, using a rolling pin, roll out the dough to form a 3/8-inch-thick circle. Use a small 2-inch glass (a shot glass would also work) to stamp out round cookies.
5. Transfer the cookies to the lined cookie sheet, placing the cookies about a 1/2-inch apart (they will not spread). Use the prongs of a fork to make two little marks (like on a button) in the center of each disc.
6. Bake the cookies in the middle of the oven until firm to the touch, 40 to 45 minutes. They will have a rich, chocolate aroma but as with any shortbread, should not have browned. Let rest for 5 minutes before transferring to a rack to cool completely.