Muscovado sugar is dark in color, intensely flavored, and less refined than most other sugars. Look for it in specialty stores or mail-order outlets. In this recipe, it imparts a molasses-like flavor to the gingery cake roll.
Heat oven to 350°F. Coat 15 x 10 x 1-inch jelly-roll pan with nonstick cooking spray. Line bottom of pan with waxed paper; coat paper.
In medium bowl, whisk together flour, baking powder, baking soda, ginger, orange rind and salt.
In large bowl, beat eggs on medium speed until foamy and slightly thickened, about 3 minutes. Add sugar gradually, breaking apart with hands. Beat in oil, followed by buttermilk and vanilla. Stir in the flour mixture. Pour batter into prepared pan, spreading to edges.
Bake at 350°F for 20 minutes.
Remove cake from oven. Dust top with confectioners sugar. Immediately invert cake onto clean kitchen towel and remove waxed paper. Roll up cake with towel, beginning with short end. Let cool to room temperature, about 1 hour.
Meanwhile, in large bowl, combine heavy cream, sugar and orange rind. With electric mixer, beat until stiff peaks form, but texture is still smooth.
Once cake has cooled, carefully unroll. Gently spread marmalade over the unrolled cake. Top marmalade with 1 cup whipped cream, leaving 1/2-inch border on short ends. Roll up cake without towel, enclosing filling. Transfer to serving tray. Frost cake with remaining whipped cream. Refrigerate up to 24 hours. Garnish with Sugared Orange Peel.
With zester, remove peel from orange. Place in small saucepan with 1-3/4 cups water and bring to a boil. Boil 10 minutes, uncovered, and drain off water. Add another 1-3/4 cups water and bring to a boil again. Boil 10 minutes and drain. Let cool. Meanwhile, whisk together 2 tablespoons warm water and 2 teaspoons powdered egg white. Dip cooled orange peels in the egg white, allowing excess to drip back into the bowl. Transfer to small bowl of granulated sugar. Toss to coat with sugar, then transfer to sheet of waxed paper to dry.