1. Preheat oven to 170 C (fan-forced). Spray a 20cm (base measurement) round cake pan with cooking spray. Line the base and side with baking paper.
2. Put the spread, lime zest, lime juice, Equal and coconut into a small saucepan. Heat over medium heat, stirring occasionally, or until hot. Pour into a large bowl and set aside for 15 minutes to cool. Whisk in the eggs, buttermilk, vanilla essence and coconut essence.
3. Combine the flours in a medium bowl. Add to the Equal mixture and mix until well combined. Using electric beaters whisk the eggwhites until soft peaks form. Fold into the cake batter. Spoon mixture into the lined pan. Smooth the surface. Bake for 35-40 minutes or until a skewer inserted into the centre comes out clean.
4. Set aside in the pan for 15 minutes before turning out onto a wire rack to cool completely. Sprinkle with equal to serve, if you like.
NUTRITION INFO PER SERVE: 534kJ, protein 4.5g, total fat 5.4g (sat. fat 2.6g), cholesterol 25.1mg, carbs 14.3g, fibre 1.8g, sodium 158mg. Carb exchanges: 1. GI estimate: medium.