Grease bottom and sides of two 15 x 10 x 3 cm jellyroll pans with vegetable oil, and line with wax paper; grease and flour wax paper. Set aside. Beat egg yolks in a large bowl at high speed of an electric mixer until thick and lemon colored. Gradually add quarter cup sugar to egg yolks, beating constantly. Beat in vanilla. Beat egg whites until foamy. Gradually add remaining half cup sugar, 1 tablespoon at a time, beating until stiff peaks form. Fold egg whites into yolk mixture. Combine flour, baking powder, and salt; gently fold flour mixture, one third at a time, into egg mixture. Spread batter evenly into prepared pans; bake at 200ºC or 5 minutes. When cake is done, turn out onto wire racks to cool completely. Peel off wax paper. Stack the two layers on top of each other to allow even slicing. Using a long serrated knife, slice layers crosswise into strips of the following widths: 3- 1 cmes, 8 cm, 2- 1 cmes, 5 cm, 1- 1 cmes, 3 cm, and 1 cm. Spread one side of both of the 3- 0.5-inch strips with a thin layer of Satiny Chocolate Frosting. Top each strip with a 8 cm strip, keeping edges even on one lengthwise side. Forming two stacks of strips, repeat spreading thin layers of frosting, and topping with successively smaller cake strips, keeping edges even, until all cake strips are used. (Stacks will be slanted on one side, with layers running horizontal; each stack of cake strips represents half the triangle.)Turn stacks onto jellyroll pan, even edges down (layers now run vertical). Cover cake stacks with aluminum foil, and place a weight (packages of cake or pancake mix) on the slanted side of 1 hour. Recipe continues on Chocolate Triangle Cake-Part 2. ----