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

Instructions

1. 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.
2. 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.)
3. For filling: 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 400°F. 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.)
4. 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.
5. Position rack in bottom third of oven; preheat to 400°F. Place puree in large bowl. Whisk in brown sugar and next 6 ingredients. Brush crust with beaten egg white. Transfer filling to crust.
6. 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.)