For the cake, preheat oven to 375ºF. Line base of 11 x 17 inches jelly roll pan with parchment paper; set aside.
In medium bowl, sift together flour, pumpkin pie spice and baking powder; set aside. In large bowl, beat egg yolks until frothy with electric mixer. Add 1/2 cup sugar; continue beating 3-5 minutes. Add pumpkin and flour mixture; mix until well combined.
In separate bowl, beat egg whites until frothy with electric mixer. Add lemon juice; continue beating 2 minutes. Gradually add remaining 1/2 cup sugar; continue beating until soft peaks form. Sprinkle ground pecans over egg whites; gently fold inches Fold yolk mixture into egg white mixture. Spread evenly into prepared pan.
Bake 20-25 minutes. Remove cake from oven. Gently loosen edges of cake from pan. Carefully turn cake onto cooling rack lined with a clean kitchen towel. Cool cake 3-5 minutes. Carefully remove parchment paper. Starting at a short edge, roll up cake with kitchen towel. Transfer rolled cake to cooling rack; cool completely.
For icing, in large bowl, beat cream cheese, melted chocolate and caramel topping with electric mixer. Gently stir in whipped topping. To fill cake, gently unroll cake. Spread about 1/3 of the icing evenly over surface. Gently re-roll cake (without kitchen towel). Trim off ends of roll using serrated knife. Transfer to serving platter.
Spatula ice pumpkin roll. Alternate rows of pecan halves and tip #21 icing shells.
Cover and refrigerate 2-3 hours or until ready to serve.