Serves about 12.
For the cake, preheat oven to 375°F. Grease then line bottom of jelly-roll pan with parchment paper. Grease 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. Gently fold ground pecans into egg whites. 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 long edge, roll up cake with kitchen towel. Transfer rolled cake to cooling rack; cool completely.
For the filling and icing, beat cream cheese and caramel topping in large bowl with electric mixer. Gently fold in whipped topping. To fill cake, gently unroll cake. Spread 2 cups filling evenly over surface; gently re-roll cake (without kitchen towel). Trim off ends of roll using serrated knife. Transfer roll to platter. Ice smooth with icing mixture.
Add rows of tip 21 shells; arrange whole pecans in rows between shell rows. Cover and refrigerate 2-3 hours or until ready to serve.