Line a 6-quart oval slow cooker with nonstick pan lining paper. Transfer Pastry Crust to prepared cooker (pastry should extend 2 to 3 inches up the sides). If desired, use a fork to press top of pastry to lining paper.
In a medium bowl toss together the next six ingredients (through cinnamon). Stir in cream. Spoon mixture into crust in cooker. Sprinkle with Streusel Topper.
Cover and cook on high for 3 to 3 1/2 hours or until filling is bubbly and pastry is golden, giving crockery liner a half-turn halfway through, if possible. Turn off cooker. Let stand, uncovered, 1 hour. If desired, serve with ice cream.
In a bowl combine oats, flour, and brown sugar. Using a pastry blender, cut in butter until mixture resembles coarse crumbs. Stir in pecans.
In a bowl stir together flour and salt. Using a pastry blender, cut in shortening and butter until pea size. Sprinkle 1 tablespoon of the water over part of the mixture; toss with a fork. Push moistened pastry to side of bowl. Repeat moistening flour, gradually adding water until dough begins to come together. Gather it into a ball, kneading gently until it holds together.