Let piecrusts stand according to package directions. For filling, in a medium bowl beat together cream cheese, pumpkin and egg yolk. Stir in sugar, flour, and pumpkin pie spice. Set aside.
Roll out 1 crust on lightly floured surface with floured rolling pin into 11-inch circle. Using a 2-1/2 to 3 -inch round cookie cutter, cut 11 to 12 rounds from crust.
Place about 1 teaspoon of the filling on half the pastry circles. Moisten edges of pastry circles with a little water. Fold in half and seal edges with tines of a fork to seal. Repeat with remaining crust and filling.
In a large skillet that is at least 3-inches deep, heat 1-inch of oil over medium heat to 375°F. Add 5 pies at a time and fry 2 to 3 minutes or until golden brown, turning once. Drain on paper towels. Serve warm. Sprinkle with sugar. Serve with sweetened whipped cream, if desired.