Whisk the flour, baking powder, salt, and baking soda, together in a medium bowl.
Melt the butter in a saucepan over medium heat or in the microwave oven. Remove pan from the heat, and add the bittersweet chocolate, set aside until melted.
Whisk the eggs, yolk, brown sugar, and vanilla together in a medium bowl then slowly whisk in melted chocolate mixture.
Stir in the flour mixture to make a loose dough. Don't over work the dough. Fold in the chocolate covered raisins. Cover with plastic wrap and refrigerate until firm, about 2 hours.
Alternate Method for Food Processor owners:.
Melt butter in micro.
Finely chop chocolate in food processor with metal blade.
Pour in warm melted butter and process till smooth.
Add vanilla, brown sugar, pulse to blend. Add slightly beaten eggs and yolk pulse to blend.
Whisk together flour, baking soda baking powder and salt add to chocolate mixture and pulse to blend.
Remove dough and and fold in chocolate covered raisins.
Cover with plastic wrap and refrigerate until firm, about 2 hours.
Preheat oven to 350°F.
Line a baking sheet with parchment paper. Form dough into balls, about 2 inches or 1 1/2 ounces each, and put on the prepared baking sheets, leaving a couple inches between the cookies. Bake about 13 to 15 minutes. Cool on a rack.