Poach chicken in broth until cooked through. Cool in broth. Shred chicken. Save broth for another use. Set aside.

Heat oil in heavy large skillet over medium heat. Add onion and stir until golden brown. Add paprika, cumin and oregano and stir until fragrant. Add shredded chicken and stir well. Season to taste with salt and pepper.

Using grater, grate corn from cob (WilliamsSonoma sells a special gadget for grating corn right into a bowl). If using canned or frozen corn, pulse in food processor until coarsely pureed. Melt butter in heavy large skillet over medium heat. Add corn, sugar and salt. Gradually stir in enough milk and cook until mixture is slightly thick. Stir in basil.

Preheat oven to 400 degrees F. Spoon chicken mixture into 2quart baking dish. Arrange hardboiled eggs, olives and raisins over. Pour corn mixture over, smoothing top to cover filling completely. Sprinkle powdered sugar over top. Bake until crust is golden brown and firm to touch, about 40 minutes. Serve hot.