Peel, core and cut the pears into chunks. Place the pears in a bowl and add the lemon juice, sugar, salt, ground cinnamon and ground nutmeg. Set aside.
For the topping: Combine the flour, sugar, brown sugar, oatmeal and butter in a bowl. Mix well until well combined.
Pour the pear mixture in the baking dish. Sprinkle the topping evenly over the pears.
Bake until the topping is crisp and golden brown and the pear filling bubbles slowly, about 50 minutes. Serve warm.