Position a rack in the center of the oven and preheat to 350 degrees . Grease a 10 1/2-by-15 1/2-inch jellyroll pan and line with parchment. Using an electric mixer, beat the egg yolks and 3 tablespoons granulated sugar at high speed until pale and thick, 5 minutes. Fold in the flour and orange peel; transfer to a large bowl.
Using the electric mixer fitted with the whisk attachment, in a clean and dry bowl, whip the egg whites and salt at medium speed for 1 minute. Beat in the remaining 3 tablespoons granulated sugar at high speed until stiff, 1 to 2 minutes. Fold half of the egg white mixture into the yolk mixture; fold in the remaining whites. Spread the batter in the prepared pan and bake until golden and springy, about 15 minutes.
Immediately dust the cake with confectioners sugar and loosen the edges with a knife. Lay a kitchen towel, then a cooling rack, on top of the cake and invert. Remove the pan and peel off the parchment. Roll up the cake lengthwise in the towel and let cool, about 30 minutes.
Meanwhile, place 2 tablespoons cold water in a heatproof bowl. Sprinkle the gelatin in and let stand until softened. Microwave for 1 minute and stir to dissolve. Stir in 1/4 cup cream and transfer to a medium bowl. Add the remaining 1 cup cream and 2 tablespoons confectioners sugar and beat until thick. Fold in the peaches. In a saucepan, simmer the pear juice over medium heat until reduced by a third; let cool. Stir in the liqueur.
Unroll the cake. Using a pastry brush, dab the cake with half of the pear syrup. Spread the peach cream on top and roll up the cake lengthwise. Transfer to a platter and refrigerate for 3 hours. Dust the cake with more confectioners sugar, slice and drizzle with the remaining pear syrup.