Heat oven to 400°F. Place cookie sheet on oven rack.
In large bowl, stir together granulated sugar, 3 tablespoons flour, the cinnamon and nutmeg. Stir in apples and raisins; toss to coat. Spoon into frozen pie crust.
In medium bowl, mix topping ingredients except walnuts with pastry blender or fork until crumbly; stir in walnuts. Sprinkle over filling.
Bake on cookie sheet 20 minutes. Place sheet of foil over pie to prevent excessive browning. Bake 20 to 30 minutes longer or until filling is bubbly and topping is golden brown. Cool at least 30 minutes before serving.