Preheat oven 200°C fan forced. Grease an 8 cup capacity roasting pan or ovenproof dish.
Peel, halve and core the pears. Arrange in the pan. Pour over the pear nectar. Press a sheet baking paper onto the surface of the pears. Cover tightly with foil. Bake 30 minutes, or until pears are almost cooked, when a skewer is inserted there should still be some resistance.
Meanwhile, for crumble, combine the flours and nutmeg in a bowl. Add the butter, using fingertips rub butter into the flour until the mixture resembles coarse breadcrumbs. Stir in the brown sugar and oats, use fingers to mix until crumble begins to clump together.
Remove the baking paper and foil from the pears. Cool 10 minutes. Top with the crumble. Return to the oven and bake, 30 minutes or until top is golden and pears tender. Serve hot with ice cream and maple syrup.