1 1/2 cups all purpose flour3/4 cup unsweetened cocoa powder (I use 1/2 cup)
1 cup plus 2 tablespoons sugar (I use 1 cup)
1/4 teaspoon salt
1/4 teaspoon baking soda
14 tablespoons (1 3/4 sticks) UNsalted butter, slightly softened
3 tablespoons whole milk
1 teaspoon pure vanilla extract
Put the flour, cocoa, sugar, salt and baking soda in the bowl of your food processor and pulse several times to mix thoroughly.
Cut the SLIGHTLY softened butter into 12 chunks and add them to the flour mixture. Pulse several times.
In a small cup, mix the milk and vanilla and drizzle it into the cookie batter while the food processor is running. Continue pulsing until the batter clumps around the blade or the sides of the bowl.
Transfer dough to the counter (no extra flour needed) and knead a few times to form into a 12" x 2" log. Cover in plastic wrap and chill at least an hour. I like to square off the sides of the log to give me more of a square cookie.
The original recipe says to slice into 1/4" thick slices, but I find that 1/8" slices are better. Bake them on parchment lined cookie sheets (1 1/2" apart) in a pre-heated 375° oven, for 12-15 minutes. My electric oven takes 13 minutes.
Cool the cookies on the cookie sheet for a couple minutes, then place them on a wire rack. They will crisp up as they cool.
You can store these cookies in an airtight container for up to two weeks or they can be frozen up to 2 months, so they are a perfect "make ahead" baking project.