In a small saucepan, melt the butter.
Turn off the heat, add the brown sugar and stir until smooth.
Stir in the egg.
Stir together the flour and the baking powder into the brown sugar mixture.
Stir in the vanilla and the pecans.
Pour the batter into the prepared pan and bake for 20 minutes.
When cool, dust the top with a sifting of powdered sugar.
