1. Place flours, baking powder, sugar, and salt in a food processor; pulse 15-20 times. Add butter and cream cheese; pulse until mixture resembles coarse meal. Add water and lemon juice; pulse just until dough forms.
2. Transfer dough to a floured surface; form into a disk. Separate disk into 2 halves; wrap both tightly in plastic wrap. Chill at least 1 hour.
3. Preheat oven to 375°. Coat a 9-inch glass pie plate with cooking spray. Turn 1 dough half out onto a lightly floured surface. Roll into a 13-inch round; transfer to parchment paper. Cover and refrigerate. Fit remaining circle of dough into pie plate; trim edge, leaving a 1/2-inch overhang. Using a fork, lightly pierce dough all over; chill until firm (about 20 minutes), or freeze 10 minutes.
4. In a large bowl, combine apples and next 7 ingredients (through nutmeg). Spoon filling into dough in pie plate; top with chilled dough. Fold overhang under edge of bottom dough; crimp overlap decoratively. Brush egg over dough; bake in middle of oven 40-50 minutes or until crust is golden and apples are tender. Let cool. Cut into 8 slices, top with 1/4 cup ice cream; serve.