Place the puff pastrty sheet on a floured surface. Cut into 9 (3") squares. Place the squares on ungreased cookie sheets. Bake at 400 degrees for 10 minutes, or until brown; cool on a wire rack. Combine the pumpkin butter, and the next 4 ingredients, beat until fluffy and light. Combine cream, vanilla and 1/4 cup powdered sugar in a chilled bowl. Beat until soft peaks form. Set aside 1/2 cup whipped cream and gently fold remaining whipped cream into the pumpkin mixture. Cover and chill pumpkin filling at least 1 hour. Carefully slice 1 pastry square in half to make 2 layers. Spoon about 3 Tbs. filling onto the bottom layer, top with second puff pastry layer. Repeat procedure with the remaining pumpkin filling and pastry squares. Chill up to 2 hours. Top each Napoleon with a dollop of reserved whipped cream.