Preheat oven to 350°F (175°C) , centering oven rack. Prepare a 11 x 17-inch jelly roll pan by brushing it with butter, shortening, or nonstick baking spray, then line it with a sheet of parchment paper and grease again. Lightly dust pan with flour (except if using spray) and tap pan to remove any excess flour. Sift All Dry Ingredients Together: Cake flour, baking powder baking soda, cinnamon, mace, ginger, allspice, and salt, stirring well to combine, set aside. Using an electric mixer, beat egg yolks with dark brown sugar, at medium-high speed, until sugar is incorporated. On highest speed, beat eggs, until they are very pale yellow, fluffy, and mousse-like in texture and volume, about 4 to 5 minutes. By hand with a rubber spatula, fold in dry ingredients alternately with the pumpkin puree. Set aside. In a clean, dry, grease-free bowl of an electric mixer, beat egg whites with cream of tartar at low to medium speed until foamy. Gradually increase speed to the highest setting, while slowly adding the granulated sugar. Beat only until soft peaks form. Take 1/3 of softly beaten whites and stir them into the reserved pumpkin/yolk mixture to "temper" it. Gently fold in the remaining whites, using a rubber spatula, cutting the mixture from top to bottom with the spatula while rotating the bowl counterclockwise. Do not over mix or egg whites will deflate. Pour batter into prepared jelly roll pan, smooth and level the top of the batter using an offset metal (icing) spatula. Bake for 18 to 20 minutes, until cake is evenly browned and a toothpick or skewer inserted in center comes out clean. Remove cake from oven and immediately cover the top with a sheet of parchment or wax paper, and a clean, damp dish towel. Set the jelly roll pan on a wire cooling rack to cool cake completely. To Prepare Filling: Using an electric mixer fitted with the whip attachment, whisk heavy cream at medium speed, gradually increasing speed to it's highest setting. Beat until cream forms soft peaks. Add maple syrup in a steady stream, then cinnamon, nutmeg and sugar. Continue to beat at high speed until cream has stiffened and peaks stand upright. To Assemble: Flip cake out of pan onto the sheet of parchment paper laid on top and carefully peel off bottom layer of paper adhered to cake, discard. Gently spread cream mixture over the cake using a metal icing spatula to reach all the edges, covering the cakes' surface in an even layer. Starting at either the long or short end of cake (I prefer the short end) roll "jelly roll fashion" slowly and evenly, rolling the cake on top of itself until you reach the other end. Gather the parchment paper underneath the cake like a sling to support it, and transfer it to your serving plate by simply rolling it out of it's sling onto the plate so the seam is on the bottom. To serve, dust top of cake with powdered sugar and if desired, decorate the top with a few swirls of extra whipped cream. A nice addition too is a sprinkling of maple flavored or spiced nuts of your choice, and a small pool of warm maple caramel on the side.
