1Preheat oven to 375 degrees. In a bowl, mix granulated sugar, brown sugar, flour, cinnamon, nutmeg, salt, and ginger. Add pumpkin, milk, and eggs; whisk until well blended. Pour mixture into unbaked 10-inch pie pastry in pan. Sprinkle walnut streusel evenly over filling. Bake on the bottom rack until a knife inserted in center comes out clean, 60 to 65 minutes. Set on a rack until cool to touch, about 2 hours. Cut into wedges. Serve with whipped cream.
Mix flour, sugar, ginger, cinnamon, and nutmeg in medium bowl. Add butter; rub in with fingertips until coarse meal forms. Stir in nuts.