Finely crush 2 cups (500 mL) of the Honey Shreddies; place in large bowl along with flour and half of the sugar. Cut in butter until mixture resembles coarse meal. Reserve 1/2 cup (125 mL) of the crumble; set aside.
Line 8-inch (20 cm) square baking dish with enough parchment paper to overhang edges. Press remaining crumble into prepared baking dish; set aside.
Stir together blueberries, remaining sugar, cornstarch, lemon juice and cinnamon. Let stand for 15 minutes. Pour filling over crust.
With fingertips, combine remaining Honey Shreddies and reserved crumble, crushing lightly to incorporate cereal. Sprinkle over filling.
Bake in preheated 350˚F (180˚C) oven for 40 to 60 minutes or until topping is golden brown and filling is bubbling. Let cool completely. Remove from pan and cut into 8 bars. Refrigerate until ready to serve.
If using frozen blueberries, do not thaw beforehand; adjust bake time as needed.