Preheat the oven to 170-180°C (340-350°F) fan bake.
Line your square cake tin.
Place the sultanas in a pot with enough water to cover them. Simmer for 15 minutes.
Strain and return the pot to the stove top, add the butter and melt on a low heat.
Cream the eggs, sugar and almond essence until pale in colour.
Fold through the flour and baking powder to the creamed mixture.
Next fold in the sultana mixture.
Pour the batter into your lined tin and bake for 45 minutes.