Preheat the oven to 350°F (180°C). Line a 9x13-inch baking dish with parchment paper.

Place the flour, cornflour, brown sugar, and salt in a medium bowl and whisk to combine. Add the melted butter and using a fork, stir until it forms a thick, sandy dough. It should be fairly moist and will seem a bit greasy at this point.

Transfer the mixture to the prepared baking dish and press evenly into the bottom. (It will seem like a thin crust but don't worry because it will rise up once baked)

Bake for roughly 18-20 minutes, or until the crust set and a very light golden. Let the crust cool for 30 minutes before adding the filling.

Place the butter, brown sugar, and maple syrup in a medium saucepan over medium heat until the butter has melted and the sugar has dissolved.

Remove from the heat and whisk in the heavy cream, vanilla, and salt. Fold in the pecans. At this point, the topping will be very thin and liquidy.

Pour the mixture over the crust and spread the pecans evenly.

Bake for roughly 22-25 minutes or until the mixture is hot and very bubbly around the edges.

Remove from the oven and allow to cool and set for a minimum of 4 hours. (you can also make them the day before)

Remove from the pan and cut into 24 squares and enjoy! Store leftovers in an air-tight container at room temperature.