Preheat the oven to 350°F. Place the pear slices in a greased 1-quart baking dish. Sprinkle them with lemon juice.
In a large bowl, combine the sugar, oats, flour, cinnamon, ginger and nutmeg. Cut in the butter until crumbly. Then, stir in the nuts. Sprinkle the topping over the pears. Editor's Tip: Keep the butter in the fridge until you're ready to use it. Using extra-cold butter will help form big crumbles in the topping.
Bake for 25 to 30 minutes or until the topping is golden brown and the fruit is bubbly.
