1. Preheat the oven to 350°F (175°C) and grease a baking dish with butter.

2. In a mixing bowl, combine all-purpose flour, brown sugar, and cinnamon. Cut in the butter until the mixture resembles coarse crumbs.

3. Press the mixture into the bottom of the prepared baking dish to form a crust layer.

4. Bake the crust for 15 minutes until lightly golden brown.

5. In a saucepan, melt the peanut butter over low heat until smooth. Pour the melted peanut butter over the baked crust layer.

6. Sprinkle crushed cornflake cereal on top of the peanut butter layer, pressing down lightly to adhere.

7. Bake for an additional 10 minutes until the cereal is toasted.

8. Let cool completely, then dust with confectioners sugar before cutting into bars and serving.