In a large bowl stir together mascarpone cheese, powdered sugar, pumpkin, ricotta, and pumpkin pie spice until smooth. Stir in 1/4 cup of the nuts. Set aside.

In a chilled mixing bowl beat cream with an electric mixer until stiff peaks form. Fold into pumpkin mixture. If desired, cover and chill up to 4 hours To serve, spoon pumpkin mixture into a self-sealing plastic bag. Snip a 3/4-inch hole in one corner. Pipe filling into cannoli shells so pumpkin filling extends from ends. Sprinkle cannoli ends with remaining nuts. Arrange on a serving platter; sprinkle with sugar. Makes 12 servings.

*Note: If purchased cannoli shells are not available, brush one side of sixteen 4-inch flour tortillas (trim larger tortillas if necessary) with cooking oil. Roll, forming a tube shape; secure with a wooden toothpick. Gently place a rolled piece of foil in the center for support. Place on a baking sheet; brush outside with oil and bake in a 375 degree F oven about 15 minutes or until golden brown. Place on a wire rack to cool. Remove foil and toothpicks; fill with pumpkin mixture. Makes 16 shells (allows for breakage).