Make about 25
12 ounces bittersweet or semisweet chocolate, chopped
¼ cup margarine
²/3 cup roasted salted macadamia nuts
²/3 cup slivered almonds
½ cup matzah cake meal
¼ teaspoon baking powder
3 large eggs
½ cup sugar
Stir chocolate and margarine in medium bowl, set over saucepan of simmering water until melted and smooth, cool 10 minutes. Using on/off turn, blend macadamias and almonds with matzah cake meal in processor until nuts are finely ground. Add baking powder and pulse to blend. Whisk eggs and ½ cup sugar in large bowl to blend. Stir chocolate mixture into egg mixture. Add nut-flour mixture, stir just to blend. Chill dough until firm enough to scoop. About 4 hours.
Line 2 large baking sheets with parchment paper. Roll dough by rounded tablespoonfuls between palms to form balls. Divide between prepared sheets. Chill until firm, about 1 hour. Can be made 1 day ahead. Cover and keep chilled.
Preheat oven to 350 degrees. Roll dough balls in powdered sugar to coat thickly, return to prepared sheets. Bake until cookies puff and form cracks and tester inserted into center form cracks and tester inserted into center of cookies comes out with a few moist crumbs attached, about 18 minutes.
Cool cookies completely on sheets on racks and store in airtight container.