Ingredients

  • 1 1/3 cups all purpose flour
  • 1 tablespoon sugar
  • 1/2 teaspoon salt
  • 6 tablespoons chilled unsalted butter, cut into small pieces
  • 2 tablespoons chilled solid vegetable shortening, cut into small pieces
  • 3 tablespoons (or more) ice water
  • 2 large red-skinned sweet potatoes (yams; 13/4 pounds)
  • 1 cup (packed) golden brown sugar
  • 1 cup whipping cream
  • 3 large eggs
  • 1 teaspoon vanilla extract
  • 3/4 teaspoon ground cinnamon
  • 1/4 teaspoon ground mace
  • 1/4 teaspoon salt
  • 1 large egg white, beaten to blend

Method

  • Mix flour, sugar, and salt in processor.
  • Add butter and shortening; using on/off turns, cut in until mixture resembles coarse meal.
  • Drizzle 3 tablespoons ice water over mixture.
  • Process until moist clumps form, adding more ice water by teaspoonfuls if dry.
  • Gather dough into ball; flatten into disk.
  • Wrap in plastic; chill until firm, about 30 minutes.
  • Roll out dough on floured surface to 14-inch round.
  • Transfer to 9-inch-diameter glass pie dish.
  • Fold overhang under.
  • Crimp edges decoratively.
  • (Crust can be made 2 days ahead.
  • Cover; chill.)
  • Pierce potatoes with fork.
  • Cook in microwave on high until tender, about 6 minutes per side.
  • Cut open; cool completely.
  • Scrape potato flesh into bowl; mash until smooth.
  • Measure enough potato puree to equal 1 1/2 cups.
  • Position rack in bottom third of oven; preheat to 400F.
  • Place puree in large bowl.
  • Whisk in brown sugar and next 6 ingredients.
  • Brush crust with beaten egg white.
  • Transfer filling to crust.
  • Bake pie until filling is puffed around edges and set in center, about 45 minutes.
  • Transfer to rack; cool.
  • (Can be made 1 day ahead.
  • Cover; refrigerate.)