Grease and line the base of the brownie pan. Pre-heat oven to 180 deg C (350 deg F).

Place butter in a medium sized pan. Set it over a low fire and melt the butter gently. Add the sugar and ground cinnamon and stir until smooth and melted. Remove from heat and set aside to cool for a few minutes.

Using a wooden spoon, add the lightly beaten eggs into the butter-sugar mixture and beat well until thoroughly combined. Sift in the flour and baking powder, then stir until just combined.

Add the lightly toasted pecan halves, and mix in gently, but do not over-stir the batter. Scoop out the batter into the prepared pan, and level the surface of the batter evenly.

Bake in the centre of the oven for about 20 to 25 minutes until golden brown, or until a metal or bamboo skewer inserted halfway between the sides and the centre emerges free of sticky batter. Remove from oven and let cool in the pan for 5 minutes. Then loosen and remove from the pan, and place on a cooling rack to cool completely.

When completely cooled, cut into 15 squares, or into larger or smaller squares as desired. Serve warm. If storing, keep in an air-tight container and consume within 4 days.