Preheat oven to 350ºF. Pile pears into an 8x8" glass baking dish and toss with the brown sugar and cinnamon. In a medium bowl, combine the topping ingredients using your fingers to squeeze it all together until no dry flour remains. Sprinkle evenly over the pears. Bake in centre of oven until filling is bubbling at the edges, about 50 minutes, tenting with aluminium foil if topping is browning too quickly.