1 cup all-purpose flour
1/3 cup unsweetened cocoa powder
Ό tsp. baking powder
1½ tsp. kosher salt
2 sticks unsalted butter, softened
1 large egg
1 Tbsp. whole milk
1 tsp. vanilla extract
1½ cups 61-percent bittersweet chocolate chips or bittersweet chocolate, finely chopped
Sift together the flour, cocoa powder, baking powder and salt into a medium bowl. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment (or in a large bowl using a handheld mixer), cream the butter and sugar on medium speed until light and fluffy, about 4 minutes. Add the egg, mixing well. Add the dry ingredients and continue beating until the batter is smooth. Add the milk and vanilla, then add the chocolate chips, beating until combined.
Turn the dough out onto a cool surface, form it into a disk, and wrap in plastic wrap. Refrigerate until firm, approximately 2 hours.
Position the racks in the upper and lower thirds of the oven and heat the oven to 350 degrees. Line two heavy, large baking sheets with parchment paper or silicone liners.
Using a 1-ounce scoop, scoop the dough onto the lined baking sheets, spacing the cookies 2 inches apart, or use a measuring spoon to scoop heaping tablespoons of dough on to the sheets. Let the dough come to room temperature.
Bake the cookies for 11 minutes, or until they lose their shine. Let cool on the baking sheets on cooling racks for 10 minutes.
Using an offset spatula, transfer the cookies to a cooling rack to cool completely.
The cookies can be stored in an airtight container up to 4 days (These cookies are quite fragile and do not freeze well).