Ingredients:

  • 1/2 cup (113g) unsalted butter, softened
  • 3/4 cup (150g) granulated sugar
  • 1 large egg, room temperature
  • 1 tsp (5ml) vanilla extract
  • 2 cups (250g) all-purpose flour
  • 1/2 cup (45g) dutch-process cocoa powder
  • 1 tsp (4g) cream of tartar
  • 1/2 tsp (3g) baking soda
  • 1/4 tsp (1.5g) salt
  • 1/4 cup (50g) granulated sugar
  • 1 tbsp (8g) ground cinnamon

Instructions:

  1. Beat the softened butter and granulated sugar together until the mixture looks pale and fluffy (about 2-3 minutes). Add the egg and vanilla extract, beating on medium speed until the batter is smooth and velvety.
  2. In a separate bowl, whisk together the flour, cocoa powder, cream of tartar, baking soda, and salt. Gradually fold the dry ingredients into the butter mixture. Mix until just combined; stop the moment you see no more streaks of flour to keep the cookies tender.
  3. Scoop rounded tablespoons of dough and roll them into 1-inch balls.
  4. Roll each ball thoroughly in the cinnamon-sugar mixture until completely coated.
  5. Place the balls 2 inches apart on a parchment-lined sheet. Bake at 350°F (175°C) for 8-10 minutes. Pull them out when the edges are set but the centers still look slightly soft and underbaked.