Whipped cream and additional chopped walnuts, optional
In a small bowl, combine 1/4 cup brown sugar, walnuts and butter until crumbly. Press onto the bottom of pastry shell. In a large bowl, whisk the eggs, pumpkin, extract, cinnamon, salt, mace, ginger and remaining brown sugar until blended; stir in cream.
Pour into pastry shell. Cover edges loosely with foil. Bake at 400° for 10 minutes. Reduce heat to 350°; bake 40-45 minutes longer or until a knife inserted in the center comes out clean. Remove foil. Cool on a wire rack.
Garnish with whipped cream and additional walnuts if desired. Refrigerate leftovers.