• Preheat the oven to 375°F and butter the bottom and sides of a 1-1/2 quart baking dish.

Prepare the topping:

• Place the corn flakes in a food storage bag and using a rolling pin, crush them into coarse crumbs. You should end up with 1/3 to 1/2 cup. Transfer the cornflake crumbs to a separate bowl, and add the sugar, flour, and cinnamon. Stir in the melted butter, combine thoroughly, and set aside.

Prepare the filling:

• Rinse the blueberries under cool running water, spread on a kitchen towel, and gently pat them dry. Transfer to a mixing bowl, sprinkle with cornstarch and cinnamon, and toss to coat. Add the lemon juice and mix well. Taste, and if desired, add the sugar.
• Add about half of the cereal mixture to the blueberries, combine gently, and transfer to the prepared baking dish, then crumble the remainder of the topping evenly over the berries.

Bake the blueberry crisp:

• Cover the dish with aluminum foil and bake until the berries are tender, 30 to 35 minutes. Uncover and return to the oven for 8 to 10 minutes longer, or until the topping is crisp and golden brown and the berries are thickened and bubbly.

Cool and serve:

• Allow the crisp to cool for at least 30 minutes, then spoon into individual serving dishes. If desired, top with fresh whipped cream or vanilla ice cream.