Place puff pastry sheet on floured surface. Cut into 9 (3-inch) squares. Place squares on ungreased cookie sheets. Bake at 400° for 10 minutes or until brown; cool on wire rack.
Combine pumpkin butter and next 4 ingredients; beat until light and fluffy.
Combine cream, vanilla extract, and 1/4 cup powdered sugar in a chilled mixing bowl. Beat until soft peaks form. Set aside 1/2 cup whipped cream and gently fold remaining whipped cream into 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 tablespoons filling onto bottom layer; top with the second puff pastry layer. Repeat procedure with remaining pumpkin filling and remaining pastry squares. Chill up to 2 hours. Top each Napoleon with a dollop of reserved whipped cream. Garnish, if desired.