To make sweet tart crust: In medium bowl, stir flour, walnuts and powdered sugar. Stir in butter and egg. Using fork, stir well until soft dough forms. Gather into ball and wrap tightly.

Refrigerate at least 1 hour, or until dough is easy to handle.

Preheat oven to 350 F and coat 9-inch tart pan with removable bottom with nonstick cooking spray.

Lay pastry dough on lightly floured board and roll into 11-inch circle. Press dough into bottom and sides of prepared pan and poke with fork on bottom and sides. Bake 20 minutes.

To make filling: In medium bowl, whisk pumpkin and cream cheese until smooth. Add brown sugar, pumpkin pie spice, vanilla extract, egg and egg yolk, beating until incorporated.

Pour into prepared crust and top with walnuts. Bake 40 minutes, or until filling is set when pan is gently tapped.

Remove from oven and let cool. Cover and refrigerate until ready to serve.

Serve each slice with dollop of whipped cream, if desired.