Peel and core the pears and apples and cut them into large chunks. Place the fruit in a large bowl and toss with the cranberries, zests, juices, granulated sugar, flour, cinnamon, and nutmeg. Pour into a 9 by 12 by 2-inch baking dish.
For the topping:
Combine the flour, sugars, salt, oatmeal, and cold butter in the bowl of an electric mixer fitted with a paddle attachment. Mix on low speed for 1 to 2 minutes, or until the mixture is in large crumbles. Sprinkle evenly over the fruit, covering the fruit completely.
Place the baking dish on a parchment-lined sheet pan and bake for 50 minutes to 1 hour, until the top is brown and the fruit is bubbly. Serve warm.
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