Preheat the oven to 300 F. Grease a 9X13 cake pan and then line it with parchment paper. Set aside.

Place the egg whites in a large bowl. Make sure that your bowl and beaters are clean and dry. Begin whipping the egg whites--when they are foamy, add a pinch of the cream of tartar. Continue whipping, and when soft peaks have formed, sprinkle 1/4 cup of sugar over the egg whites. Continue whipping until stiff peaks have formed--be careful not to overwhip and dry the egg whites out. Shake the beaters off.

Place the egg yolks and 1/2 cup of sugar into another large bowl. Whip (you can use the same beater as long as you do the egg whites first) the egg yolks and sugar until they are very pale yellow and ribbons form when the beater is dragged across the surface of the mixture.

Fold the melted chocolate mixture into the egg yolks. When it is almost blended, add the egg whites and fold them in until almost blended. Then sprinkle the liquor and polenta (or cornmeal) on top of the mixture and fold it in. Be careful not to deflate the egg whites, but do fold the mixture until completely blended now. Pour the cake batter into the prepared cake pan. Spread the top even with a rubber spatula.

Place the cake into the oven. Bake until the center is firm and a cake tester inserted into the center of the cake comes out either clean or with just a few crumbs attached, 60-75 minutes. Let cool completely in the pan before slicing. Dust with confectioners' sugar before serving.