4 tablespoons (56 grams) unsalted butter
8 ounces (225 grams) semisweet or bittersweet chocolate, coarsely chopped
1/2 cup (100 grams) granulated white sugar
2 large eggs
2 teaspoons pure vanilla extract
1 1/2 cups (195 grams) all-purpose flour
1/4 teaspoon salt
1/2 teaspoon baking powder
1 cup (110 grams) confectioners (powdered or icing) sugar, sifted
In a stainless steel bowl, placed over a saucepan of simmering water, melt the chocolate and butter. Remove from heat and set aside.
In the bowl of your electric mixer (or with a hand mixer), beat the eggs and sugar until thick, pale, and fluffy. (When you slowly raise the beaters the batter will fall back into the bowl in slow ribbons.) At this point beat in the vanilla extract and then stir in the melted chocolate mixture.
In a separate bowl whisk together the flour, salt, and baking powder. Add dry ingredients to the chocolate mixture, stirring just until incorporated. Cover with plastic wrap and refrigerate until firm enough to shape into balls (3-4 hours or overnight).
Preheat oven to 350 degrees F (170 degrees C) and place rack in center of oven. Line two baking sheets with parchment paper.
Place the confectioners sugar in a shallow bowl. With lightly greased hands, roll a small amount of chilled dough to form a 1 inch (2.5 cm) ball. Place the ball of dough into the confectioners sugar and roll the ball in the sugar until it is completely coated and no chocolate shows through. Gently lift the sugar-covered ball, tapping off excess sugar, and place on prepared baking sheet. Continue forming cookies, spacing about 2 inches (5 cm) apart on baking sheets. (If you find the dough getting too soft for rolling into balls, return to the refrigerator and let chill until firm.)
Bake cookies for 8 to 10 minutes or just until the edges are slightly firm but the centers are still soft. (For moist chewy cookies do not over bake. Over baking these cookies will cause them to be dry.) Remove from oven and place on a wire rack to cool.