** The Orange/Almond Sponge Sheet ** Preparing the pan. Preheat the oven to 375 degrees. Line the jelly-roll pan with buttered wax paper, leaving a 2-inch overhang at each end. Roll flour in the pan and shake out excess.
The cake batter. Using a wire whisk or hand-held electric mixer, beat the 3 egg yolks in a 3-quart bowl, gradually sprinkling in the 1/2 cup of sugar. When the mixture is thick and pale yellow, beat in the grated orange rind and juice, the almonds, and the almond extract. Slowly sift in the flour, while blending with the whisk. In a very clean separate bowl with clean beaters, beat the egg whites to soft peaks; sprinkle in the 3 tbsp of sugar and continue beating to form stiff, shining peaks. Stir a quarter of the egg whites into the batter; delicately fold in the rest.
Baking the jelly roll. Immediately turn the batter into the prepared pan; bang it lightly but firmly on your work surface to settle it, and place it at once in the middle level of the preheated 375 degree oven. Bake about 10 minutes, until it has very lightly colored and the top is springy-do not overbake or the cake will crack when you roll it up.
Cooling and storing. Sprinkle the top of the cake with a 1/16 inch layer of confectioner's sugar; cover with a sheet of wax paper and a lightly dampened towel. Reverse onto a tray or baking sheet. Then whlle the cake is still warm, holding an end of the wax paper, lift off the jelly-roll pan. Carefully peel the wax paper off the cake. Sift another 1/16-inch layer of sugar over the cake and roll it up in the damp towel; place in a plashc bag to keep it from drying out, and refrigerate. (The cake must be cold before you fill and frost it.)
** Ahead-of-time note: The sponge sheet will keep nicely 2 or 3 days in the refrigerator or you may freeze it for several weeks - but to prevent its breaking, be sure to let it defrost completely before unrolling it.
** The Meringue Base-Italian Meringue **
Beat the egg whites in the electric mixer until foaming through out; add the salt and cream of tartar and continue beating until soft peaks are formed. Turn mixer speed to slow. In a small saucepan bring the sugar and 1/2 cup water to the simmer, remove from heat, and swirl the pan until the sugar has dissolved completely and the liquid is perfectly clear. Cover the pan tightly and boil to the soft-ball stage (238 degrees). Using moderately slow speed, gradually whip the hot syrup into the egg whites; increase speed to fast and continue at high speed for 5 rninutes, until egg whites form stiff shining peaks and have completely cooled. Plan to use the meringue promptly.
** Meringue Mushrooms **
Preheat the oven to 200 degrees. Scoop a quarter of the me ringue into the pastry bag and squeeze out 8 to 10 half-inch domes on the pastry sheet, to serve as mushroom caps. Hold the l/8-inch tube over the end of the pastry bag and squeeze out 8 to 10 conical shapes 3/4 inch high, for the stems. Bake about 1 hour in the middle level of the oven, until the meringues push easily off the pastry sheet-they should color no more than a darkish cream. Return unused meringue to the main mixture. ** Ahead-of-time note: Meringues may be made in advance and frozen.
** The Directions will continue in Part #3 **