For Cake: You'll need three layers, or three times the recipe given. If you have only two 9 inch layer pans that are 2 inches deep, you may want to make two layers the night before you assemble the cake. Adjust rack to center of oven; preheat oven to 350 degrees F. Grease pans with solid vegetable shortening. Line bottoms with wax paper cut to fit, grease paper, and dust the entire inside lightly with flour, knocking out any excess. Set aside. 

In small, heavy-bottomed, nonreactive pot, combine buttermilk and butter. Place over low heat, stirring often, until butter is melted. Set aside to cool to lukewarm. 

Meanwhile, sift flour, sugar, cocoa powder, baking soda, and salt into medium bowl. When buttermilk mixture is lukewarm, add it to the beaten egg and vanilla; with fork, beat to mix well. All at once, add liquid to sifted dry ingredients. With whisk, stir until dry ingredients are moistened, then beat briskly until well-mixed and smooth (a few small lumps are OK). Batter will be thin. Pour into prepared pan. Holding pan with both hands, tilt slightly so that batter runs up sides of pan a bit. From a height of about 3 inches above a flat surface, drop filled pan three times (this helps to distribute air bubbles evenly--don't hold the pan too high above the flat surface!). 

Bake in preheated oven for 30 to 35 minutes, or until toothpick inserted in center emerges with a few moist crumbs still clinging to it. Do not overbake. Cool in pan 10 to 15 minutes. Gently loosen cake from edges of pan; invert onto cooling rack. Gently peel wax paper from bottom of layer, then re-invert to cool right side up. Cool completely before frosting or storing. 

For Frosting: In large, heatproof bowl, combine chopped chocolates and butter. Set over simmering water on low heat (water should not touch bottom of bowl). Stir frequently until melted and smooth. Remove from heat and hot water; set aside near stovetop. 

In one quart heavy-bottomed, nonreactive saucepan, combine eggs, sugar, and salt. By hand, beat thoroughly to combine well. Add orange juice, then water, beating to mix after each addition. Cook over medium heat, stirring constantly, until mixture registers 170 degrees F on a candy thermometer. Immediately remove from heat. 

Quickly strain about one-quarter of hot egg mixture into melted chocolate mixture and whisk well to combine. Gradually strain remaining hot egg mixture into chocolate mixture, whisking to mix after each addition. Scrape sides and bottom of bowl periodically with rubber spatula to ensure thorough blending. Cool slightly, then chill. Whisk occasionally until frosting begins to thicken, then scrape bowl sides and bottom with rubber spatula and whisk frequently until frosting is of spreading consistency. (Alternatively, place bowl of frosting into larger, shallower pan half full of ice and cold water. Whisk frequently; scrape bottom and sides of bowl often. This method is much quicker, but the frosting must be watched carefully, as it can harden before you know it.) When ready, frosting will have thickened considerably, and it will hold soft peaks (just like a meringue or whipped cream) when the whisk is lifted from it. 

Important note: while frosting chills (beforehand, if you're using the quick-chilling ice-and- water method), prepare the cake layers, as they should be ready for assembly when the frosting is. If necessary, trim tops of layers so they are flat. Using a large, sharp, serrated knife, carefully halve each layer horizontally (this will give you six thin layers). Use one thin layer, the top half of one of the original three you baked, to make the crumbs for the outside of the cake. To do this, pull the thin layer into very small pieces with a fork and/or your fingers (because the cake is so dense and moist, the resulting small pieces will look better than they would if you tried to actually crumble the cake). Place these very small pieces into a bowl, and cover airtight. Cover the remaining thin layers so they won't dry out. Get a serving plate ready; you'll need a plate with a flat portion in the center at least 9½ inches in diameter. 

When the frosting is ready, place a dab of it in the center of the serving plate. Place what was originally the top half of one of the three layers you baked, cut side up, onto the serving plate, on top of the dab of frosting. Spread about ½ cup of the frosting onto the cut surface, spreading it just to the edges. Place the bottom half of this original layer, cut side down, on top of the frosting, and spread it with another ½ cup of frosting, just to the edges. Repeat. At this point, you'll have one thin layer of cake left, the bottom half of one of the original three you baked. Place this, cut side down, on top of the cake. Press gently, and straighten the sides if necessary. Frost sides and top with remaining frosting. 

With your fingers, pick up some of the cake "crumbs" you made earlier. Flatten your hand so it's just slightly cupped, and pat crumbs onto the side of the cake. Some crumbs will fall onto the serving plate--that's OK, just pick them up and re-apply them. Put the crumbs on randomly, but spread them out as evenly as possible; the entire cake surface won't be covered with them. Save some crumbs to pat onto the top of the cake. Chill cake about 30 minutes. If necessary, use your hands to gently re-shape the sides. Chill until cold before covering tightly. Chill at least 2 hours before serving. 

To cut, you'll need a large, sharp knife. Cut thin slices, as this is quite rich. Store in refrigerator, tightly wrapped, for up to three days, or freeze. 

Yield: At least 12 servings!