Preheat oven to 375º
Coat bottom and sides of 15x10 inch jelly roll pan with cooking spray, and line with wax paper. Coat wax paper with cooking spray; set aside
Beat eggs at medium speed with an electric mixer 5 minutes or until thick and lemon colored; gradually add sugar, beating until well combined. Combine flour and next 6 ingredients. Gradually add to egg mixture beating well. Combine pumpkin, pecans (if using), and 1 teaspoon of lemon juice, and gradually add to mixture, beating well. Spread batter evenly into prepared pan.
Bake at 375º for 15 minutes or until a wooden pick inserted in center comes out clean.
Sift 1/2 cup powdered sugar in 15x10 inch rectangle on a clean, dry dish towel. Run a knife around the edges of pan to loosen cake, and turn cake out onto prepared towel. Peel wax paper off cake. Starting at narrow end, roll up cake and towel together; place seam side down, on a wire rack to cool completely.
Beat cream cheese and butter at medium speed with electric mixer until creamy; gradually add remaining 1 cup powdered sugar, beating until smooth. Stir in vanilla and 1 tsp lemon juice.
Unroll cake; remove towel. Spread cream cheese mixture on cake, leaving a 1-inch border around edges. Re-roll cake without towel, and place seam side down, on a serving platter. Cover and chill at least 3 hours.
Garnish with powdered sugar