Chocolate Crackle Cookies

8 ounces bittersweet chocolate, melted and cooled
1-1/4 cups all-purpose flour
1/2 cup Dutch cocoa powder
2 teaspoons baking powder
1/4 teaspoon salt
8 tablespoons (1 stick) unsalted butter, room temperature
1-1/2 cups light-brown sugar, firmly packed
2 large eggs
1 teaspoon pure vanilla extract
1/3 cup milk
1 cup granulated sugar
1 cup confectioners' sugar, plus more for rolling

1. Heat oven to 350 degrees.

2. Melt chocolate over medium heat in a heat-proof bowl or the top of a double boiler set over a pan of simmering water. Set aside to cool. Sift together flour, cocoa, baking powder, and salt.

3. With an electric mixer, beat butter and light-brown sugar until light and fluffy. Add eggs and vanilla, and beat until well combined. Add melted chocolate. With mixer on low speed, alternate adding dry ingredients and milk until just combined. Divide the dough into quarters, wrap with plastic wrap, and chill in the refrigerator until firm, about 2 hours.

4. Divide each piece into 16 1-inch balls. Roll in granulated sugar to coat, then in confectioners sugar to coat. Space 2 inches apart on baking sheets lined with parchment paper.

5. Bake until surfaces crack, about 14 minutes, rotating sheets halfway through. Let cool on wire racks.