Preheat oven to 375°F. Prepare 8-inch square baking dish (or a 10 x 8-inch dish) by lightly spraying with cooking spray.
In a large bowl, combine pears, lemon juice, ginger, granulated sugar and flour, and stir until the pears are evenly coated. Arrange in baking dish.
In a large mixing bowl, combine butter, flour, oats, brown sugar, cinnamon, and salt. Use a pastry cutter, fork, or your fingers to blend the butter into the dry ingredients. The mixture should hold together in large clumps.
Sprinkle topping evenly over the pear mixture.
Bake for 40 minutes, or until filling is bubbling, pears are tender, and top is golden brown. Cool slightly before serving.
Serve warm with vanilla ice cream.
Notes
If you really like ginger, feel free to double the amount. Or, if you're not wild about it, omit the ginger completely. Add a half teaspoon of cinnamon to the filling instead.