TOSS pears, Œ cup (60 mL) flour, salt, sugar, cinnamon and vanilla together in a large bowl. Set aside.
COMBINE œ cup (125 mL) flour, oats and brown sugar in a bowl. Cut in butter with a pastry cutter or fingertips until mixture resembles large crumbs. Stir in pecans.
SPOON pear mixture into pie shell. Top with crumble mixture and place pie on a baking sheet. Carefully cover the edges of the crust with aluminum foil to prevent burning.
BAKE in preheated oven for 35 minutes. Remove foil and continue baking for an additional 15 to 20 minutes or until pastry and crumble are golden brown and pears are tender.