Pre-heat the oven to 180C (390F) fan-forced and grease and line line a 30x20cm shallow baking tin with paper so it extends over the long sides.

Pour the brown sugar, butter and vanilla into a large bowl and stir to combine.

Add the eggs and mix them through.

Sift in the flour, baking powder and salt and stir them through then fold in the pecans.

Spread the batter into the tin and bake for 25-30 minutes or until a cake tester comes out clean.

Leave it to cool completely in the tin.

Make the icing by beating the butter until light and creamy. Add the icing sugar and beat until combined.

Dissolve the coffee in the water and then beat it into the icing. Continue to beat until it is light and fluffy. A little more water might be needed to get it to a spreadable consistency.

Spread the cooled slice with icing and slice into squares.

Store it in an airtight container for up to 5 days.