Grease bottom of a 15" x 10" x 1" jellyroll pan; line with wax paper. Grease and flour wax paper and sides of pan. Arrange pansies, stems up, in pan.
Beat egg yolks in a large mixing bowl at high speed of an electric mixer 5 minutes or until thick and pale. Gradually add 1/3 cup sugar, beating well. Stir in oil and lemon extract.
Beat egg whites in a large bowl at high speed until foamy. Gradually add 2/3 cup sugar, 1 tablespoon at a time, beating until stiff peaks form and sugar dissolves (2 to 4 minutes). Gently fold beaten whites into egg yolk mixture.
Combine flour, baking powder, and salt; gradually fold into egg yolk mixture. Carefully spoon batter into prepared pan. Bake at 350° for 12 to 14 minutes or until top springs back when touched.
Sift powdered sugar in a 15" x 10" rectangle on a cloth towel. When cake is done, immediately loosen from sides of pan. Turn out onto sugared towel. Peel off wax paper. Turn cake over, pansy side down. Starting at narrow end, roll up cake and towel together; let cool on a wire rack, seam side down. Unroll cake and remove towel. Spread cake with Lemon-Cream Cheese Filling; carefully reroll cake.