1/3 cup (2-1/3 ounces) granulated sugar
1-1/2 cups plus 2 tablespoons (8-1/8 ounces) all-purpose flour
3/4 cup (2-1/4 ounces) unsweetened cocoa powder
1/2 teaspoon baking soda
1/4 teaspoon baking powder
14 tablespoons butter
1-3/4 cups packed (12-1/4 ounces) dark brown sugar
1 tablespoon vanilla extract
1/2 teaspoon salt
1 large egg plus 1 egg yolk
1. Pour the granulated sugar in a shallow bowl and set aside. In a medium bowl, stir together the flour, cocoa, baking soda, and baking powder.
2. In a large bowl, melt 10 tablespoons of the butter in the microwave. Microwave the butter until just melted. Stir in the remaining 4 tablespoons butter until melted. Allow the butter to cool for 5-10 minutes (it should be about 90-95 degrees on an instant read thermometer).
3. Whisk the brown sugar, vanilla, and salt into the melted butter until the mixture is completely smooth. Whisk in the egg and egg yolk until smooth. Stir in the flour mixture until just combined. Chill the dough briefly to firm up if it's too soft. Scoop into dough balls, about 2 tablespoons per cookie. Freeze for baking later if desired.
4. When ready to bake, preheat the oven to 350 degrees F.
5. Roll the dough balls in the granulated sugar and place on lined (with parchment or silpat liners) baking sheets.
6. Bake the cookies, one sheet at a time, until they have puffed and have cracks running through the top, about 12-14 minutes. Don't overbake or the cookies will be dry. Transfer the cookies to a baking rack to cool completely.