ADD sweet potatoes (including syrup) to a food processor with remaining FILLING ingredients.
PROCESS the FILLING mixture until smooth.
POUR mixture into two 9-inch frozen pie shells.
BAKE 55-65 minutes (centers will still move slightly).
PLACE pies on wire racks to cool.
WHIP heavy whipping cream into a medium bowl with electric beater until it thickens; add remaining TOPPING ingredients gradually and continue whipping until peaks form.
SPREAD whipped cream TOPPING over cooled pies.
DUST each pie with ground cinnamon if desired as a GARNISH for either TOPPING.