Heat oven to 350 degrees. Arrange two racks in center of oven. Line bottoms of three 8- by 2-inch buttered cake pans with parchment paper. Dust bottoms and sides with extra cocoa; tap out excess. Sift the 3/4 cup cocoa; whisk with boiling water. Let cool. In electric mixer fitted with the paddle attachment, cream butter on low until light and fluffy, and gradually beat in the sugar until light and fluffy, 3 to 4 minutes; scrape down sides twice. Beat in the vanilla. Gradually drizzle in eggs, beating between each addition until batter is no longer slick, scraping down sides twice. Sift flour, baking soda, and salt. Whisk together the cocoa mixture with the milk. With mixer on low speed, alternate adding flour mixture and cocoa mixture, a little of each at a time, starting and ending with the flour. Divide evenly into the three pans. Bake 35 to 45 minutes, rotating the pans for even baking, if needed, until a cake tester inserted into the center of each comes out clean. Let cool on a wire rack, about 15 minutes. Remove the cakes from the pans, and return to rack to cool, tops up. Make the Chocolate Frosting: Place chocolate and cream in heavy saucepan. Cook over low heat, stirring constantly with a rubber spatula, until combined and thickened, 20 to 25 minutes. Increase heat to medium-low, and cook, stirring, 3 minutes more. Remove from heat; stir in corn syrup. Transfer to a large metal bowl; refrigerate. Check every 15 to 20 minutes; stir until cool enough to spread, about 2 hours. (Makes 6 cups) To assemble cake, remove papers from bottoms of cakes. Save the prettiest layer for the top. Place one layer on the serving platter, spread with 1 1/2 cups of the chocolate frosting, and repeat with second layer, top with third. Cover outside of cake with remaining 3 cups frosting. Makes three 8 inch layers. Source: "Martha Stewart Living Magazine, May 1997" S(Formatted for MC5): "by Lynn Thomas - Lynn_Thomas@prodigy.net" Yield: "3 eight-inch layers" Per serving: 7670 Calories (kcal); 636g Total Fat; (73% calories from fat); 30g Protein; 497g Carbohydrate; 2083mg Cholesterol; 2856mg Sodium Food Exchanges: 0 Grain(Starch); 0 Lean Meat; 0 Vegetable; 0 Fruit; 127 Fat; 30 1/2 Other Carbohydrates Recipe by: Martha Stewart Converted by MM_Buster v2.0n.