¼ cup Hershey’s Special Dark Cocoa powder
1½ teaspoons cream of tartar
½ teaspoon baking soda
¼ teaspoon salt
10 tablespoons butter, at room temperature
¾ cup granulated sugar
¼ cup packed light brown sugar
1 large egg
1 teaspoon vanilla
1/3 cup white sanding sugar
1¾ teaspoons Saigon Cinnamon
Preheat oven to 375 degrees.
Whisk flour, cocoa powder, cream of tartar, baking soda and salt in a medium bowl.
Beat butter granulated sugar and brown sugar in a large bowl with a mixer on medium speed until creamy, about 2 minutes.
Increase the speed to medium high and beat until fluffy, about 2 more minutes.
Beat in egg and vanilla. Reduce the mixer speed to low and beat in the flour mixture until just combined.
Combine the sanding sugar and cinnamon in a small shallow bowl.
Form heaping teaspoonfuls of dough into balls with damp hands.
Toss in in the cinnamon sugar to coat.
Arrange about 2-inches apart on 2 baking sheets.
Bake until cookies are set around the edge, 8 to 9 minutes.
Let cool 2 minutes on the baking sheets, then transfer to a rack to cool completely.
Makes about 2½ dozens cookies