In a double boiler, melt together chopped chocolate and butter, stirring until smooth. Set aside to cool.

Combine flour, cocoa powder, baking powder, and salt in a medium bowl and whisk together.

In a large bowl, beat together sugar, eggs, and vanilla. Add melted chocolate mixture on low speed.

Slowly add flour mixture and beat on low until blended, then stir in chocolate chips.

Cover the bowl and refrigerate until dough is firm, about 2 hours.

Preheat the oven to 325°F. Scoop rounded tablespoons and roll into balls, then cover with confectioner's sugar. Press them slightly into place on a baking sheet.

Bake for 13-17 minutes until tops are cracked and puffed.