Preheat oven to 350 degrees F. Position rack in center of oven.
In a heatproof bowl, cover the raisins with very warm grappa to 1 inch above the level of the raisins. Soak until the raisins are plumped, about 3 to 5 minutes.
In a double boiler, melt 8 ounces bittersweet chocolate. Keep warm.
Whisk together the flour, cocoa, baking powder and salt. Put aside.
With an electric mixer, cream the butter, brown sugar, and white sugar until well blended and lighter in color.
Add the eggs, 1 at a time, scraping the sides of the bowl as needed. Blend in the warm melted chocolate, 2 tablespoons warm grappa, and the vanilla extract.
At low speed, add the dry ingredients in 2 or 3 additions until just combined.
Fold in 12 ounces chocolate chunks and raisins. Chill the dough for at least 1 hour.
Using lightly buttered cookie sheets or parchment paper, drop dough by generous tablespoons onto cookie sheet, about 3 inches apart to allow for spreading.
Bake for 10 to 12 minutes. The cookies will look underdone, but will continue to cook and firm as they cool. Let stand for 1 to 2 minutes before transferring to cooling racks to cool completely.
Store in a tightly sealed container.
Recipe courtesy of Jennifer Dietrick, Hellertown, PA