2cupsall-purpose flour(260 grams) -- weigh or measure by spooning into cups and leveling
⅔cupDutch process cocoa powder (weigh for best results)(70 grams)
½teaspoonbaking soda
½teaspooncream of tartar
1teaspoonsalt
1/16teaspooncinnamon
1cupunsalted butter (2 sticks)(228 grams)
1cupsugar(200 grams)
¾cuppacked light brown sugar(150 grams)
2largemedium or large eggs, bring to room temperature(90 grams)
1teaspoonvanilla extract
4-6ounceschopped dark or bittersweet chocolate or 1 cup bittersweet chips or whatever chocolate you like
Instructions
Whisk together the flour, cocoa powder, baking soda, cream of tartar, salt and the tiny bit of cinnamon. Be sure everything is evenly blended. Set aside.
Soften the butter so that it is squishy, almost but not quite melted. I do this by standing the stick on its end in the microwave, heating on high for 6 seconds, then turning and standing the butter on its other end and heating for 4 to 6 seconds.
In a stand mixer with the paddle attached, cream the softened butter and both sugars for about 4 minutes, stopping to scrape the bowl once or twice.
Add the eggs and beat on low until blended, then increase mixer speed and beat until it is mixed in. Beat in the vanilla.
By hand or using lowest speed of mixer, stir in the flour mixture, being careful not to over-beat Batter will be very thick. Stir in the chocolate.
Adjust oven rack so that it's in the bottom third of the oven. Preheat oven to 325 degrees F. Line two light colored baking sheets with parchment paper. Also have ready a rimmed baking sheet or 9x13 inch cake pan, which you will put under the baking sheet.
Using a large cookie scoop, scoop out 12 big rounds of dough onto a couple of dinner plates. This dough is messy and sticky. Use your fingers, preferably dampened with a little water, to form the dough into balls, then gently flatten the tops so you have inch 1-inch thick mounds (for thicker cookies). If you want big flat (thin) cookies, flatten to about ½ inch thick. You can also chill the dough at this point if you'd like, but it's not necessary. I usually do anyway.
Arrange as many rounds as you want to bake (I recommend starting with 2 just to get the timing right) on one of the parchment lined baking sheets.
Put the smaller rimmed pan in the oven, then set the baking sheet with the cookie dough on top of it.
Bake at 325 F. for 20 to 25 minutes. Check at 20.
To cool, slide the parchment onto a cool counter and let cool completely.
Convection: If using convection, bake at 330 and check at 18 minutes. The time will probably be about the same, but you need to reduce the temperature slightly.
Notes
To keep the cookies really soft, I've been testing with Pillsbury unbleached, Food Lion bleached and Wegmans pastry flour. There's no reason you can't use King Arthur, you just might get a slightly stiffer cookie.