Preheat the oven to 375 degrees. Spray an 8x8 baking dish with vegetable spray and set aside. Place the flour, sugar, ginger and butter into the bowl of a food processor and pulse until mixture resembles coarse meal. Transfer to a bowl and with your fingers, work the mixture, squeezing to create a lumpy, crumbly texture. Add the almonds and toss to combine. Refrigerate until ready to top the crumble.
Peel the pears and halve them with a sharp knife. Cut the halves in half again and remove the core and stem. Cut pears into thin slices lengthwise. Transfer pears to a large bowl and sprinkle with the lemon juice. Add the minced ginger and toss together. Sprinkle the pears with cinnamon and nutmeg.
In a small bowl, mix the water and cornstarch together to form a slurry. Pour over the pears and toss to coat the pears with the slurry and spices. Transfer the pears to the prepared baking dish.
Liberally sprinkle the almond topping over the pear filling. Bake for 50 minutes to 1 hour until the fruit is tender, but not mushy and the topping is a warm, golden color.
If the fruit is tender, but the topping is pale, place it under the broiler for 4-5 minutes to get a little color. Serve warm with a scoop of vanilla or a drizzle of cream.