PreparationFor crust: Whisk flour, sugar, and salt in large bowl to blend. Add butter. Using back of fork, cut in butter until very coarse meal forms. Add 3 tablespoons ice water. Toss until dough comes together in moist clumps, adding more water by teaspoonfuls if dough is dry. Gather dough into ball; flatten into disk. Wrap in plastic and chill at least 1 hour and up to 1 day. For streusel: Combine flour, maple sugar, butter, and salt in medium bowl. Using back of fork or fingertips, rub in butter until moist clumps form. Transfer 1/4 cup streusel to small bowl and reserve for filling. Mix walnuts into remaining streusel. Chill streusel while preparing pie. For filling: Stir maple sugar, lemon juice, vanilla, spices, and salt in large bowl to blend. Add apples and 1/4 cup reserved streusel mixture; toss to combine. Let stand 15 minutes, tossing occasionally. Position rack in bottom third of oven and preheat to 400°F. Roll out dough on floured surface to 13-inch round. Transfer to 9-inch-diameter pie dish. Fold overhang under. Crimp edge decoratively. Spoon filling into prepared crust, mounding in center. Dot with 1 tablespoon butter. Sprinkle streusel over filling; press lightly to adhere. Bake pie until apples are tender and streusel is crisp and golden brown, covering edge of crust with foil if browning too quickly, about 1 hour 5 minutes. Let pie stand 15 minutes. Serve warm or at room temperature with ice cream.
PreparationFor crust: Whisk flour, sugar, and salt in large bowl to blend. Add butter. Using back of fork, cut in butter until very coarse meal forms. Add 3 tablespoons ice water. Toss until dough comes together in moist clumps, adding more water by teaspoonfuls if dough is dry. Gather dough into ball; flatten into disk. Wrap in plastic and chill at least 1 hour and up to 1 day. For streusel: Combine flour, maple sugar, butter, and salt in medium bowl. Using back of fork or fingertips, rub in butter until moist clumps form. Transfer 1/4 cup streusel to small bowl and reserve for filling. Mix walnuts into remaining streusel. Chill streusel while preparing pie. For filling: Stir maple sugar, lemon juice, vanilla, spices, and salt in large bowl to blend. Add apples and 1/4 cup reserved streusel mixture; toss to combine. Let stand 15 minutes, tossing occasionally. Position rack in bottom third of oven and preheat to 400°F. Roll out dough on floured surface to 13-inch round. Transfer to 9-inch-diameter pie dish. Fold overhang under. Crimp edge decoratively. Spoon filling into prepared crust, mounding in center. Dot with 1 tablespoon butter. Sprinkle streusel over filling; press lightly to adhere. Bake pie until apples are tender and streusel is crisp and golden brown, covering edge of crust with foil if browning too quickly, about 1 hour 5 minutes. Let pie stand 15 minutes. Serve warm or at room temperature with ice cream.